What is exactly the difference between the \"old\" Managed C++ and the \"new\" C++/CLI?
Managed C++ (Managed Extensions for C++) is a set of microsoft specific keywords used with standard C++ syntax to allow compile managed code. IT was designed such that programmers could start using .NET as fast as possible and made porting native code to .NET platform very easy. It used IJW (it just works) priciple, which made programming porting to .NET easier, but it also had lot of flaws.
C++/CLI is a new language. It solved lot of problems of Managed C++, made .NET programming more powerful and is accepted as standard, but also introduces new syntax, new keywords, and is more more different from unmanaged C++ than older Managed C++.