Hi,
Check out this microsoft website, it is well explained.
Windows Server 2008 R2, now with Service Pack 1 (SP1) provides
new virtualization technology that enables you to deliver more advanced capabilities to your business for increased IT efficiency and agility. Whether you want to consolidate servers, build a
private cloud or offer
Virtual Desktop Infrastructure, the addition of these powerful virtualization features enables you to take your datacenter and desktop virtualization strategy to a new level.
http://www.microsoft.com/windowsserver2008/en/us/product-information.aspx