C# is a different language than C or C++. It's kind of a dirivative of C++ (and therfore C).
It's a managed language, because it handles things for you like garbage collection. If you really want a detailed list about what the differences are you need to check places like
http://msdn.microsoft.com/
C# can use DirectX as well, so long as it's 9.0 or later.
But yes, they're simply libraries that allow you draw and use advanced graphics.