The simplest explanation (even if somewhat inaccurate at times) is that C++.NET simply adds the ability to use .NET code in C++ apps. Of course, since you use .NET code (even if you don't want to, it still translates to .NET), the .NET Framework is required. For example, what you use in C# (e.g. System.Console.WriteLine) should be able to be used in C++.NET in a C++ syntax -
Code:
using namespace System; //System namespace
int main () {
Console::WriteLine("Hello World!");
return 0;
} rather than -
Code:
#include <iostream>
using namespace std;
int main () {
cout << "Hello World!" << endl;
return 0;
}