Possible Duplicate:
Difference between .NET 4 Client Profile and Full Framework download
I noticed that you can change the target platform in .NET applications to the Client Profile or the Full profile. What is the difference between the two? How should I choose which is the correct one for my project?
Summarized from MSDN:
When targeting the .NET Framework 4 Client Profile, you cannot reference an assembly that is not in the .NET Framework 4 Client Profile. Instead you must target the .NET Framework 4.
The .NET Framework 4 Client Profile does not include the following features. You must install the .NET Framework 4 to use these features in your application:
Applications that target the .NET Framework 4 Client Profile typically improve the deployment experience by having smaller download sizes and quicker install times. An application that targets the .NET Framework 4 Client Profile has a smaller redistribution package that installs the minimum set of client assemblies on the user’s computer, without requiring the full version of the .NET Framework 4 to be present.