Whether it is online MSDN library or local MSDN help, it returns all results which contains your word to search.
However, VS 2010 supports multiple languages and there are documents belongs to each languages.
For example, some API belongs to Win32 and MFC at the same time ( due to same function name ).
"Data type" documents exist for C#, C++, .NET, Win32 etc.
I have used MSDN for about 20 years, and I always wondered why there was no "option" to narrow down your search critieria like "Win32", "MFC", or nowadays "C#", ".NET" etc.
I'm not sure if MS has any plan to enhance MSDN search ( again either online or local ), but it would be great if they have.