Question : SQL Server 2008 and 2008 R2 ?

Quick question for quick point for any SQL Saint :).
are there 2 SKU's, SQL Server 2008 and SQL Server 2008 R2 ? are these two different products as the Windows 2008 and 2008 R2 are ?
if it does can you point me to any documentation.
Thanks!

Answer : SQL Server 2008 and 2008 R2 ?

Both are different editions and the new features in 2008 R2 compared to 2008 are listed below:

http://www.microsoft.com/downloads/details.aspx?FamilyID=fffaad6a-0153-4d41-b289-a3ed1d637c0d&displaylang=en

http://www.sqlmag.com/article/sql-server/sql-server-2008-r2-5-cool-new-features-.aspx
http://www.mytechmantra.com/LearnSQLServer/Microsoft_SQL_Server_2008_R2.html