SQL Server 2012 Editions
1. Standard Edition
2. Business Intelligence
3. Enterprise Edition
Developer -- The developer edition includes all the features which are available in enterprise edition, but it is only meant for development, testing and for demonstration purpose.
Web -- It is mainly focused on hosting internert facing web applications. Like Express editions it doesn't have database size restrictions, and it supports upto 64 GB RAM. It is a ideal platform for websites and web applications
Express -- This is a free edition, which can integrate with independent software vendors. It is limited to one processor and 1 GB memory and it is integrated with visual studio environment.