What are the major differences between Windows Server 2008, 2008 SP2 and 2008 R2?
Are the code bases for these OSes different?
If I'm developing applications for any one of these three, should I be worried that it might not work on the other two?
What’s the difference between Windows Server 2008, 2008 SP2 and 2008 R2
windows-server-2008windows-server-2008-r2
Best Answer
Windows Server 2008 and Windows Server 2008 SP2 are the same operating system, just at a different service pack level (Windows Server 2008 started at the SP1 level because it was released quite a bit after Windows Vista and SP1 was already out).
Windows Server 2008 R2 is the server release of Windows 7, so it's version 6.1 of the O.S.; it introduces quite a lot of new features, because it's actually a new release of the system. This is a good place to start: http://www.microsoft.com/windowsserver2008/en/us/whats-new.aspx.
There are also differences at the GUI level, because WS2008R2 uses the same new GUI introduced with Windows 7 (new taskbar, etc.).
Depending on what kind of applications you're developing, they may or may not encounter problems on different O.S. releases; you should definitely check MSDN.
The single most important point: Windows Server 2008 R2 exists only for 64-bit platforms, there's no x86 version anymore.