SQL Server 2012 is available in these editions:
- Enterprise Edition
- Standard Edition
- Business Intelligence Edition
- Developer Edition
- Web Edition, and
- Express Edition
Out of these, the Enterprise Edition is of course the one that has all the high end features for meeting the needs of a Tier-1 large scale deployment. You would recall that previously there was a DataCenter Edition available – that is no longer available now and all of it’s capabilities are now included in the Enterprise Edition itself.
The Business Intelligence Edition is a new Edition that is offered now. This is available to offer clients the full suite of powerful BI features in SQL Server 2012 like Power View, PowerPivot, enhanced reporting and analytics. Any company specifically looking at SQL Server from the perspective of BI and not interested in the full OLTP features that are found in the Enterprise Edition would opt for this one.
The Standard Edition is aimed towards customers who do not need the high end features that are available in the Enterprise or the Business Intelligence Editions.
Out of the remaining three specialized Editions, the Developer Edition (like in previous versions) has all the features of the Enterprise Edition but is meant only to be used in a Dev/QA environment and does allow for a direct upgrade to the Enterprise Edition. The Web Edition is essentially intended for the hosting service providers. It is scaled down version in terms of support for processors (max: 4) and the feature sets but is good enough to be used if you are looking for an edition to host web-sites and small scale web applications. It supports up-to 64GB of memory. The Express Edition is a free edition and has restrictions on the DB size (max: 10GB), 1 processor and 1GB of memory.
Here are some links comparing the different feature sets across the different editions available in SQL Server 2012:
SQL Server 2012 Editions: http://www.microsoft.com/sqlserver/en/us/sql-2012-editions.aspx
Article on MSDN with the Feature Comparison between the different Editions: http://msdn.microsoft.com/en-us/library/cc645993
And here is the information from MSFT in regards to licensing: http://www.microsoft.com/sqlserver/en/us/get-sql-server/licensing.aspx