VDI Infrastructure: Citrix vs. VMware

Whether you're a CIO conducting a cost-benefit analysis or an engineer evaluating platforms, comparing VDI solutions can be a challenge, especially in an ever-evolving market.

Often, marketing teams change solution names as soon as the market gets acquainted with the previous name. Add to that new features being introduced semi-annually and quickly, and you see the VDI market experiencing a high rate of change.

To assist with this challenge, I'll guide you through the basic infrastructure components of VMware and Citrix's VDI solutions and discuss how they compare.

Regardless of whichever solution is discussed, the VDI space typically requires five base components:

1. A hypervisor that allows access to the benefits of virtualization

2. A brokering service to delegate the available resources to the end user

3. A provisioning technology to scale the environment by copying an existing machine's setup

4. A web front end to provide authentication and access to the resources

5. An external gateway to ensure secure external access to the internal resources

Each vendor's product is slightly different, but they accomplish the same functional goals. Collectively, these five components integrate to provide a solution that provides access anywhere, anytime, on any device. That's the entire VDI pitch in five words.

Terminology to Know

We'll want to start with establishing some terminology for synonyms often used in the VDI space.  Let's get the product name cleared up, as both have undergone a renaming in the past few years.  What was previously known as VMware View was changed to VMware Horizon View and is now labeled VMware Horizon.

Similarly, Citrix XenApp and XenDesktop have been redubbed Citrix Virtual Apps and Desktops. Version numbers are normally included at the end of these naming conventions, with VMware following a typical numbering pattern (e.g., 7.11) and Citrix following Microsoft's lead with the concatenated year-month model (e.g., 1912).

Consider the chart below your pre-appendix for any comparable terms and use it as a reference as we continue.

Citrix Virtual Apps and Desktops

Hypervisor

Citrix's documentation touts an impressive list of compatible hosting solutions. These include Citrix Hypervisor (formerly XenServer), VMware vSphere, Microsoft Hyper-V, and the slightly newer Nutanix Acropolis for on-premise deployments. In the realm of cloud competitors, Citrix supports the two big 800-pound gorillas in the market: Amazon AWS and Microsoft Azure. (Though it's worth noting that VMWare does now, too.) 

Brokering Service

The brokering service for Citrix comes in the form of the Delivery Controller.  The Delivery Controller is responsible for:

1. Communication with the hypervisor to create and update machines

2. Communication with the database to store and retrieve assignments and entitlements of resources

3. Communication with the downstream servers to ensure the availability of the resources

Administrators interact with the Delivery Controller through either (1) Citrix Studio (a GUI-based console) or (2) Citrix Powershell SDKs.  This is where roughly 80 percent of a Citrix administrator's time is spent.

Provisioning Technology

Citrix's long-standing provisioning technology is called Provisioning Services, more commonly called PVS. PVS is a solution that provides great scalability by enabling virtual machines created on the hypervisor to network boot via a separately installed Citrix Provisioning Server that streams the requested boot image across the wire.

To give an example of how this may be beneficial, consider that a machine could essentially boot without any disk attached and store all its changes in cached memory, effectively consuming zero disk space (note: this is an extreme case. Often, PVS VMs include an attached disk for disk writes or overflow of disk writes from memory cache).

The secondary option for Citrix provisioning is Machine Creation Services (MCS). MCS allows users to duplicate an existing VM configuration by combining the base image, a snapshot, and some MCS magic to create and re-roll an effective new machine with the same configuration but a new independent identity.  

To do this, MCS effectively takes a copy of the combined base image and snapshot, combines it into a master image, and copies that master image to each storage repository that the hosting environment has access to.

From there, the new VMs are spun up, referencing that master image as a read-only disk, and additional disks are attached. The first additional disk is known as an identity disk and provides the machine with its static new identity (think computer name, SID, etc.). The other disk attached is a differencing disk, which serves as the temporary repository for any changes made to the VM's existence.

Both of these technologies have merits, but beware—both also have drawbacks. PVS is still available, but Citrix has signaled stronger support for MCS, especially in cloud/hybrid environments. Also, MCS now supports Azure and AWS as provisioning targets and supports ephemeral disks and caching improvements, making it more viable at scale.

Web Front-End

Every application needs some way for its users to interact with it. For Citrix, this is known as Storefront, which is responsible for: 

1. Handling user authentication

2. Communication with the delivery controller to enumerate user assignments

3. Storing users' resource subscriptions

Individual configurations of Storefront are called Stores, and they are configured to pull assignments from one or many delivery groups. Citrix supports various access methods via Stores, including anonymous authentication, domain authentication, domain + security token, SAML authentication, smart cards, and certificates.

After users authenticate, they are presented with a listing of their available resources, as pulled from the delivery controller's records. As they frequent specific resources or manually favorite them, a memory of their selections is cached as a subscription to provide a consistent experience.

External Gateway

Quick note on the naming conventions here. Citrix rebranded NetScaler to "Citrix ADC" around 2018, but NetScaler is now back. In 2022, NetScaler became an independent business unit again, and the product is now simply called NetScaler Gateway (not Citrix Gateway).  Either way, it is a hardened web proxy for authenticating external access requests and relaying connections to internal resources.

More than your typical web proxy, the ADC combined with the Gateway is often considered the proverbial Swiss army knife of networking. They perform a range of tasks including:

1. Content switching

2. Load balancing

3. Web-app firewall

4. SSL offloading

5. VPN services

The gateway comes in various packages, including a virtual appliance with a software license to scale its throughput to physical appliances similarly scaled to size, with an optional FIPS-compliant configuration.

Overall, the external gateway is a beast and often requires a Network/Security Administrator or someone with skills outside your typical Citrix Administrator's role.

VMware Horizon

Hypervisor

Considering VMware is the leading virtualization platform in the market, it's nice that you're allotted free licenses for vSphere with VMware Horizon. That being said, it's really the only option for on-premise deployments, as other hypervisors are not supported.

On a bright note, VMware does have a Horizon Cloud offering, which provides some flexibility by enabling Microsoft Azure, Amazon AWS, and IBM Cloud as public cloud vendors. VMware now mostly refers to this as part of the VMware Anywhere Workspace or Horizon 8 / Horizon Cloud Service umbrella.

Brokering Service

In Horizon, the View Connection servers are the brains of the operation. Similar to the delivery controllers of Citrix, the View Connection servers perform the following roles:

1. Handling and storing the entitlements of resources. 

2. Communication with the downstream resources to ensure resource availability.

You'll likely notice we left off the communication with the hypervisor portion, and for good reason.  Depending on which provisioning technology you choose, this piece may be handled by a different part of Horizon. As a side note, it's ideal that the View Admin console is completely HTML-based, so there's no need to install a separate console for administration.

Provisioning Technology

VMware Horizon uses Instant Clones as its primary provisioning technology. Instant Clones build on the same core concept as Citrix MCS—using snapshots of a base image to spin up lightweight, read-only virtual desktops quickly—but with significant performance and management improvements.

Unlike Linked Clones, which relied on the now-deprecated View Composer component, Instant Clones are fully integrated into the Horizon platform and do not require a separate provisioning service. They create VMs directly in memory from a running parent VM, drastically reducing the time it takes to provision and recompose desktops.

Each Instant Clone shares the memory and disk of its parent VM but maintains its own identity and writes changes to a differencing disk, making it both space-efficient and fast to deploy. This architecture also allows for near-instant updates and refreshes, making it easier to maintain consistent desktop environments at scale.

Instant Clones are now the default and recommended provisioning method in modern Horizon deployments.

Web Front-End

The View Connection server also handles the internal web front end. Interestingly, this service supports domain authentication, SAML authentication, domain + token authentication, and smart cards.

External Gateway

VMware Horizon uses the Unified Access Gateway (UAG) for secure external access. The UAG replaces the deprecated Security Server and supports modern authentication methods, load balancing, and integration with multiple Connection Servers—all in a lightweight, Linux-based appliance.

Citrix vs VMware: Which to Choose

Now that the stage has been set, let's get to the fun part: comparing the Citrix and VMware VDI infrastructures.

Hypervisors

Citrix clearly does a better job catering to a more diverse pool of hosting solutions. However, do consider that this is a calculated tactic by VMware. VMware's target here is to gain market share with its sector-leading technology, ESXi, and to ensure stability and consistency within the VDI experience.

Brokering Service

For the most part, a brokering service is a brokering service. The only caveats to this would be potential add-on alternatives or services that can be attached that would make a significant impact. For Citrix, there is Citrix Director, which provides a single web-based administration page for both helpdesk- and administrator-level tasks.

Think of this as a basic environment health status page combined with some helpful troubleshooting tools to diagnose and interact with user sessions. In addition, load index evaluation can be figured via Citrix Policy, which gives the Director Insight into a machine's resource strain and potential overutilization.

As for add-ons, Horizon doesn't come bundled with a comparable toolset. However, if you consider combining two alternative resources—internally developed Horizon Helpdesk Utility and vRealize for View—you'll have your solution.

Provisioning Technology

Citrix and VMware both offer two provisioning options, but the real comparison is between Citrix PVS and VMware Instant Clones.

PVS streams desktops over the network from a central server, making it highly storage-efficient but network-dependent. Instant Clones, now the default in Horizon, spin up VMs directly from a running parent in memory—faster and simpler, but reliant on solid storage performance.

Both scale well and handle enterprise workloads, so the decision typically comes down to infrastructure:

Strong network, tight storage? Go with PVS.

Want speed and simplicity? Choose Instant Clones. As with any decision of this sort, the answer will always come down to two simple words: "It depends."

Web Front-End

While very similar, I'd have to give the blue ribbon to Citrix, as Storefront provides more granular control of how you want your user experience to look and feel. In addition, Citrix has an administration console dedicated to the configuration of Storefront, whereas making changes to the View Connection interface follows a more primitive approach to locating and editing configuration files. It's not a big deal, but seeing some advances here would be nice.

External Gateway

This one’s a tradeoff between power and simplicity. Citrix NetScaler (formerly Citrix Gateway) offers far more than just remote access—it’s a full-blown ADC with load balancing, SSL offloading, VPN services, and web app firewalls. But all that flexibility comes at a cost: more licensing, more training, and a steeper learning curve. NetScaler isn’t exactly beginner-friendly.

VMware, on the other hand, uses the Unified Access Gateway (UAG) for secure external access. It’s a lightweight, Linux-based appliance that's much easier to deploy. With just a few clicks and some basic config, you're up and running—no need to master networking wizardry.

So, what do you value more: granular control with complexity, or streamlined access with minimal overhead?

The Final Verdict

Choosing between these two solutions ultimately depends on what matters most to your organization. Citrix was the first to market in the application virtualization space, and it’s still viewed as the gold standard by many enterprises. With years of development behind it, Citrix Virtual Apps and Desktops offers deep configurability and flexibility, ideal for teams that need granular control and can manage complexity.

VMware Horizon, meanwhile, has matured into a powerful VDI platform in its own right. What began as a more streamlined alternative has grown into a robust, cloud-ready solution with fast provisioning, centralized management, and strong integration across the VMware ecosystem. While it may have once been the “simple” option, Horizon now balances ease of deployment with enterprise-grade scalability.

In the end, it comes down to your priorities:

➤ Need advanced control and flexibility? Citrix may be the better fit.

➤ Want faster deployment, easier scaling, and deep cloud integration? Horizon might win out.

Sometimes, simplicity wins. Other times, you need every knob and lever. Luckily, both platforms have grown enough to offer a bit of both.