Here are few...
Windows Server 2003 R2 provides numerous ease-of-use improvements to Active Directory and new features, including cross-forest trusts, the ability to rename domains, and the ability to deactivate attributes and classes in the schema so that their definitions can be changed.
Group Policy Management Console (GPMC) provides the new framework for managing Group Policy. With GPMC, Group Policy becomes much easier to use, a benefit that will enable more organizations to better utilize Active Directory and take advantage of its powerful management features.
Your users can retrieve archived versions of their documents that are invisibly maintained on the server.
IPSec
64-Bit Computing etc
More info @
http://www.microsoft.com/windowsserv...omparison.mspx