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?


5 Answers 5


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.

  • Sorry, Massimo, that link doesn't work any more for me. It goes to microsoft.com/en-us/server-cloud/default.aspx Would you have a way to find it again?
    – Mark C
    Oct 22, 2012 at 4:28
  • No, recently Microsoft relinked ALL of its WS2008R2 documentation to WS2012... finding docs about WS2008R2 is becoming increasingly difficult.
    – Massimo
    Oct 22, 2012 at 7:06

Ok simple way of looking at it:

Windows Vista SP1 = Windows Server 2008

Windows Vista SP2 = Windows Server 2008 SP2

Windows 7 = Windows Server 2008 R2

  • As of Vista SP2/Server 2008 SP2, MS has announced the Desktop and Server OSes will be based on the same code and release (more or less) in side step. They have already announce that Win8/Server vNext will also be released together (though it'll likely be 2 to 4 years before we see them).
    – Chris S
    May 17, 2011 at 13:06
  • 2
    WTF is wrong with Microsoft? How can you hide a huge change like that inside an R2? Oct 5, 2012 at 14:51
  • @Scott Apparently Windows 7 is known internally as version 6.1.
    – Mark C
    Oct 22, 2012 at 4:29
  • 2
    @MarkC: That would be reasonable, except so many products need Win7 and not Vista - Visal Studio 2012, TFS 2012, etc. We were rather blindsided by the fact they wouldn't run on our Server 2008 SP2. Oct 22, 2012 at 13:30

THe only thing I have encountered thusfar is that Window Server 2008 R2 is much more secure than regular Windows Server 2008. For instance, I develop for SharePoint, Of which a known issue is that it "forget" to enable Local launch / activation for the IIS Wamreg COM component. In Windows Server 2008 you could just open op de Component Services window and enable all accoutns needed. In Windows Server 2008 R2 you need to go into the registry first and take ownership of the IIS WamReg registry key first before being able to change to security settings.


Okay, its a bit confusing, Windows Server 2008 is based on the WindowsNT 6.0 service pack 1 kernel. Because of this the first service pack was Service pack 2 (Windows Server 2008 SP2). Windows Server 2008 R2 is also based on the WindowsNT 6.1 Kernel (It is akin to Windows 7 much like Server 2008 is akin to Vista) with some expanded features and capabilities.

Since the kernel is the same unless your doing something fairly exotic it should be fine, remember to consult the MSDN for better info. The biggest issue I could see you running into is the ability for R2 to run without a GUI interface at all. This is probably going to be a minority of cases, it is not the default for it, default is just like any other Windows Server, I'm not sure how many will be using the ability.

  • Exactly, Windows Server 2008 is based on the 6.0 kernel (with SP1); Windows Server 2008 R2 is based on the 6.1 one, the same of Windows 7.
    – Massimo
    Aug 18, 2009 at 10:17
  • Ah yes, your right, it is the WindowsNT 6.0 service pack 1. my mistake there.
    – Shial
    Aug 18, 2009 at 12:59
  • I was going to edit your answer to correct the mistakes, but the whole thing is pretty much wrong. Also, the Core install still has a GUI, it's just strongly reduced. Parts of the .NET framework were ripped out as well; mostly related to the GUI.
    – Chris S
    May 17, 2011 at 13:12

Windows Server 2008 does not allow for BranchCache mode as does 2008 R2.

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