As I posted earlier here I've decided to try my hand at one of these but given my interests as a web developer, I'd like to know the difference between them in their real-world applications.
While I'm a web developer, please don't let that limit your answer. I'm 30...I've got years of career changing ahead of me.
Both C and C++ give you a lower level of abstraction that, with increased complexity, provides a breadth of access to underlying machine functionality that are not necessarily exposed with other languages. C++ adds the convenience (reduced development time) of a fully object oriented language which can, potentially, add an additional performance cost. In terms of real world applications, I see these languages applied in the following domains:
C# provides a managed memory model that adds a higher level of abstraction again. This level of abstraction adds convenience and improves development times, but complicates access to lower level APIs and makes specialized performance requirements problematic.
It is certainly possible to implement extremely high performance software in a managed memory environment, but awareness of the implications is essential.
The syntax of C# is certainly less demanding (and error prone) than C/C++ and has, for the initiated programmer, a shallower learning curve.
Johannes Rössel makes the valid point that the use C# Pointers, Unsafe and Unchecked keywords break through the layer of abstraction upon which C# is built. I would emphasize that type of programming is the exception to most C# development scenarios and not a fundamental part of the language (as is the case with C/C++).