C++ and C# are both programming languages that have been derived from C. However, there are some crucial differences between them.
First, the former is a lower-level language that operates on a level much closer to the machine’s hardware, whereas the latter is a high-level language. The former compiles down to machine code, while the latter compiles down to something called Common Language Runtime, and thus maintains a higher level of abstraction.
Also important is the fact that the former is highly portable and can generate code that can run on any platform, provided it is compiled correctly, whereas code written in the is Windows-specific and is used only to create applications that run on those operating systems. Furthermore, the former is, as has been said multiple times, a language that embraces multiple coding paradigms, while C# is pure object-oriented.
Finally, as a general rule, C++ is also quite complex, whereas C# has a simple hierarchy, uses simple syntax, and can be mastered quite easily.