Windows Server 2012 will be available in 2 edition only:
Both are identical in terms of features, the only difference is related to virtualization:
Standard edition includes only TWO instance while Datacenter edition includes UNLIMITED instance of Windows.
Regarding hardware consideration, Standard edition is able to support up to 4 TB of memory and up to 64 physical processor like Datacenter edition.
The licensing has been also simplified; Windows Server 2008 R2 Standard and Enterprise were licensed by the server while Windows Server 2008 R2 Datacenter Edition was licensed by the processor/socket. Now, with Windows Server 2012 editions are licensed in two processors increments, which means:
- 2 processors server needs 1 license,
- 4 processors server needs 2 licenses,
- 8 processors server needs 4 licenses.