This just frustrates me to no end…
The “R2” releases of Windows Server products is a separate OS release. The fact that they are also separate OS releases impacts their support cycles and what software packages are supported.
Most people are rather sloppy about how they refer to OS releases and use 2008 to refer to 2008 or 2008 R2. This is BAD! There are significant differences between Windows Server 2008 and 2008 R2. Failing to properly distinguish between the OS versions can lead to a number problems, especially when troubleshooting problems.
So, please, if you mean 2008 R2, say 2008 R2. If you just tell me 2008, I’m going to assume you mean Windows Server 2008.