[dopamine]

.NET framework gives you a huge list of ready-made functions to use with C#. .NET VM manages all your memory(unless you use pointers or unsafe mode code) This decreases development time at the expense of performance. When developing in any .NET language you will be mostly only using the .NET ready made functions. You can't code kernel-mode software(drivers) in .NET. Its impossible.

C++ has a lot optional libraries such as Boost, Qt, etc. C++ doesn't handle your memory, you must be aware of everything you allocate and you must free it at the appropriate moment otherwise a memory leak occur. C++ has a lot better performance. You can't compare C# and C++ in a CPU intensive task. When developing in C++ you will be using the API your OS gives you(WinAPI for Windows).

TL;DR; C# is trash for anything than a hello world application.

This reply is from personal experience and are pretty much the only worth mentioning differences.