What is the difference between c and c#?

Answer 1

There is no language named C##.
There is C, a very fast, very low level language.
There is C++ another fast, low level language. Unlike C, C++ allows object oriented programming.
There is C#, which is used for a great amount of applications in the industry today. C# is allows a high level of abstraction. It is very similar to Java.

I recommend the Wikipedia pages on these programming languages or trying a simple Hello World in each to help you understand the differences. ^_^