Q: What are the versions of Windows Server 2012 and how do they differ?

A: Microsoft has simplified the licensing of Windows Server 2012. It no longer differentiates versions based on features. As with System Center 2012, licensing now reflects virtual rights and is based on processor counts:

Each license for Windows Server 2012 Datacenter and Standard covers two physical processors, which is the same as for System Center 2012. There are no feature differences between the Standard and Datacenter editions, which have the same features, memory and processor capabilities. This means the Standard edition has features such as Failover Clustering.

CALs will still be required to access Windows Server. This now gives a common license model across Windows Server, System Center, and ECI. Additionally, note the following about these editions of Windows Server 2012:

There is no HPC, Web, or Enterprise edition of Windows Server 2012.

There is also no price change for the Windows Server 2012 Datacenter license ($4,809); however, the price did increase 22 percent (new price is $882) for Standard.  This new price reflects an increase from one to two virtual instance rights, plus all the premium features that were previously available only in Enterprise edition.

In terms of license migration, for customers with Software Assurance the following applies:

Remember that multiple licenses can be applied (stacked) to a single server to give the virtual rights you need. For example, if a physical server with two processors needed four virtual instances, then assign that server two Windows Server 2012 Standard licenses.

If six virtual instances were needed, it could be assigned three Windows Server 2012 Standard licenses. Remember that Standard edition doesn't give the mobility for the virtual instances, but Datacenter edition has unlimited virtual instance rights. A step up from Standard to Datacenter will be available.

The public announcement can be found at the Windows Server 2012 editions website  along with a licensing FAQ its download site and an overview paper also at the download site.