Understanding the difference between thin and thick clients

Deciding between thin and thick clients

Managing and delivering virtual desktops is a significant task for IT administrators to take on, but sometimes choosing the right endpoint for accessing the virtual desktop can go a long way for the user experience.

One key decision surrounding virtual desktop delivery is whether end users access their resources via a thin client or a PC running thin client software. Such PCs are commonly referred to as thick clients. Both types of endpoints have their benefits and drawbacks, so IT admins and executives should be sure they know the pros and cons of using both thin and thick clients.

Differences between thin clients and thick clients

Thin clients and thick clients -- sometimes referred to as fat clients -- differ across numerous categories, such as hardware cost, licensing and maintenance. Each organization will have different needs and preferences regarding which functions are most important.

Security

One of the primary benefits of using thin client hardware compared to thick client hardware is security. Thin client devices may not even be equipped with an internal hard drive and removable media ports, which means users can't copy data from within the network to removable media. While it is true that some thin client devices do contain a small amount of internal storage, this storage is almost always reserved for use by the device's internal OS and cannot be used for data storage or for installing applications directly onto the device.

Because thin client machines typically do not have an accessible hard drive, there is very little risk of malware infecting the client itself, though under the right circumstances the virtual desktop operating system could be infected.

Although a desktop PC can function as a thin client computer, the thin client software typically resides on top of a normal OS. As such, the device would be susceptible to many of the same types of security risks as it would be if it were operating as a regular PC within the virtual environment.

Startup costs

Initial deployment costs are a major consideration for some organizations. While it is true that thin client hardware typically has a very low price tag, the cost of deploying thin clients may be much higher than that of deploying PCs. For example, organizations that already own PCs can reuse them, which will cut down significantly on hardware costs. At the same time, organizations that start from scratch will see lower costs with thin client hardware. Some thin client devices cost as little as $300 or less out of the box. Organizations can opt for even greater savings if they purchase refurbished devices, but this may not be worth the hassle from a support perspective.

Software licensing costs

When comparing thin clients to thick clients to determine which platform is a better fit, an organization absolutely must consider software licensing costs. Traditional PCs acting as thick clients are almost always required to run a full OS, such as Windows 10 or Windows 11. This is in addition to licensing the client software and any other software that might be installed locally on the PC. As such, an organization could end up being forced to pay for two operating system licenses for each device. One of these licenses covers the local OS while the other applies to the operating system running on the virtual desktop.

A dedicated thin client device may come with its own light weight operating system. This could be a Linux kernel, or perhaps a copy of Windows Embedded. This can reduce licensing costs, since the organization would only be responsible for licensing the OS that is running on the virtual desktop.

Thin client devices could potentially incur licensing costs that thick clients do not. Some vendors offer management software for thin client devices, and this management software is often licensed on a per device basis. However, some vendors bundle the management license into the device's cost.

Licensing requirements can vary widely depending on the virtual desktop operating system that in use are using and on how the virtual desktops are being hosted. Windows 365, Microsoft's cloud desktop offering, for example, is licensed on a per user basis, not a per device basis. However, depending on which tier is in use, there may be additional licensing requirements, such as Microsoft Intune, or Entra ID Premium.

Maintenance costs

One of the big selling points of thin client hardware is that it reduces maintenance costs. Thin client devices are essentially proprietary PCs that only have their most basic components in place. As such, IT doesn't have to perform much maintenance. There are almost no moving parts, so thin client devices also tend to last a long time. However, when a problem does occur, there might be nothing that admins can do to fix it. IT may have to replace the device.

Conversely, it is usually easier to fix hardware problems that occur on a PC. Admins can replace the failed component, typically for much less than the cost of replacing an entire thin client device.

Zero clients offer the lowest per device cost, fastest boot times, and smallest attack surface of any of the client types.

Of course, this is only taking hardware maintenance into account. PCs need consistent maintenance at the software level. For example, IT must routinely install patches to keep a PC's OS, applications, and antivirus software up to date.

Power consumption

When comparing thin and thick client's power consumption, thin clients tend to consume far less power than PCs. Of course, power consumption varies among makes and models, but organizations can count on thin clients generally being far more energy efficient if that's a concern for organizations.

Flexibility

Flexibility is the category in which PCs are finally able to make up some ground. It's clear that thin client devices tend to have more advantages than PCs in virtual desktop environments, but in a business environment, the flexibility provided by PCs could make up for all these disadvantages.

For example, consider an organization that goes through a corporate buyout. The organization already has a VDI platform in place, but the organization that completed the acquisition uses mainframes. Because some users have to connect to the VDI environment and the mainframe, it is necessary to replace the existing thin client hardware with PCs.

One option is to link the PCs' network cards to the VDI environment while a secondary network card links to a mainframe gateway. Users could then run a dual monitor configuration with one screen displaying the VDI session and the other showing the mainframe session.

This functionality and level of flexibility are not possible without dedicated thin client hardware and is just one scenario showcasing how the flexibility of PCs helps organizations.

What are zero clients and are they an option?

Zero clients are a lot like thin clients, but they take things just a step further. While a thin client typically contains an embedded, lightweight operating system and some minimal hardware resources to support that OS, a zero client has no local operating system at all -- though they do contain firmware. Instead, these devices are configured to connect to a specific virtual desktop platform by using a platform specific protocol such as PC over IP or HDX.

Zero clients offer the lowest per device cost, fastest boot times, and smallest attack surface of any of the client types. Because zero clients do not include an OS, there is no internal storage device, and thus, nothing that can be infected by malware.

The low cost, simplicity, and security associated might on the surface seem to be ideal. However, this convenience and security comes at a cost. Zero clients lack any sort of flexibility. These clients are designed to do one job, and they cannot be repurposed to do something else. As such, zero clients are often a great choice for organizations that have very clearly defined goals for their endpoints. However, they probably aren't going to be the best choice for use in a highly dynamic environment.

Brien Posey is a former 22-time Microsoft MVP and a commercial astronaut candidate. In his more than 30 years in IT, he has served as a lead network engineer for the U.S. Department of Defense and a network administrator for some of the largest insurance companies in America.