I am making a SQLCLR stored procedure in Visual Studio 2012. I have these options for target platform:
Is there not a SQL Server 2008 R2 specific option? Is this because SQL 2008 R2 shares the same compatibility level of 100 with SQL Server 2008?
A 2008 and 2008R2 user database is schema compatible, hence one version for both in SSDT. In other words, there aren't any schema objects that you could add to a 2008R2 SSDT model that couldn't be created in 2008.
This isn't the same as either database version or database compatibility level.
Database compatibility level:
It is not just the compatibility level. Also the .NET options themselves are the same against both 2008 and 2008 R2.
In a word:
Not exactly, but it doesn't really matter.