First there was Windows Server 2003.  And then in 2005, Microsoft released something of a super-service-pack with new functionality, patches, and other stuff.  It was much more than a regular service pack, full of optional components that shipped on a 2nd CD.  So, it was name “Windows Server 2003 R2.”  But underneath, it’s still Windows Server 2003 at the core.

You might think that Windows Server 2008 R2 follows the same naming convention.  But you’d be wrong.

Windows Server 2008 R2 is not “Windows Server 2008 + More Good Stuff,” it’s actually much more like “Windows 7 – Server Edition.”  The core is a different (though of course related) operating system. 

Why did Microsoft do this?  I’m sure they have good reasons… investment in the Windows 2008 ‘brand,’ major/minor naming schedules, and so on. 

I’m sure that Windows 2008 R2 is a wonderful operating system.  Windows 7 seems pretty nice, after all.  But, don’t be fooled by the name and think that upgrading from Windows 2008 to Windows 2008 R2 is no big deal, its a full blown OS upgrade.