The decision between Microsoft Remote Desktop Services and Remote Desktop Session Host comes down to cost, capabilities...
Organizations looking to deploy Microsoft desktop and application virtualization have long had two primary choices: Remote Desktop Services (RDS), which is the company's solution VDI technology, and Remote Desktop Session Host (RDSH), also known as Windows Terminal Services.
Not all that long ago, RDSH was the obvious better choice. RDS was a relatively unproven technology at the start, and it also had a reputation for being ridiculously expensive to implement. Today, however, RDS is a viable -- and in many cases, better -- choice.
The case for Microsoft Remote Desktop Services
RDS has finally caught up to RDSH in terms of what the technologies are capable of. Organizations can use either approach to deliver virtualized applications and virtual desktops, and cost might not be as large of a differentiator as it once was.
The main advantage of RDS is that it is based on a true desktop operating system, so there is guaranteed application compatibility. And the transition away from physical desktops is much easier, because the virtual desktops can run exactly the same configurations, patches and applications as the existing physical desktops.
The transition will probably also be easier for users, because IT can configure the virtual desktops to look, feel and behave exactly like their current physical desktops. As such, any learning curve will be minimal.
In addition, RDS makes for easy physical/virtual desktop coexistence. Assuming that the virtual desktops are domain joined, they will be able to use the same permissions and the same group policy settings as existing physical desktops. Existing security policies should seamlessly apply to the virtual desktops.
Further, most organizations use gold images to provision physical desktops, so there is a good chance they could use these same images -- or slightly modified versions -- to provision virtual desktops.
The case for Remote Desktop Session Host
In the case of RDSH, its biggest advantage is that it has existed for a long time and really hasn't changed that much over the years. RDSH is stable, reliable and very well documented and supported.
RDS tends to be more complicated to deploy and maintain than RDSH. This complexity can mean a higher initial cost, and possibly a higher ongoing cost. (Even so, RDS costs are not nearly as out of line with RDSH as they once were.)
The major downsides are that RDSH is session based and it relies on a server operating system rather than a desktop operating system such as Windows 10. As such, some applications do not work well in RDSH environments. In some cases, it's because the application is designed for a specific version of Windows. More often, however, applications experience difficulty running in multi-session environments. There are also occasionally situations in which applications simply are not licensed for use with RDSH.
In most cases, Microsoft Remote Desktop Services is probably going to be a better choice, but there can sometimes be compelling use cases for Remote Desktop Session Host.
Does the VDI versus RDSH debate even matter?
For RDSH or VDI, use case is everything.
How to create RDSH farms with VMware Horizon.