.net is merely an environment. It is managed coding. A lot of featurers have been automated for you, especially windows programming. The logic is the same for c++ and .net. Syntactically c++ and C++.net vary a bit here and there. For instance in .net coding you do not include iostream.
Code:
//C++
cout<<"Hello";
//C++.net
Console::WriteLine(S"Hello")
//C++
int n;
cout<<"Input N: "; cin>>n;
cout<<n;
//C++.net
int n;
Console::Write(S"Input N: ") //Reads a string;
n=Int32::Parse(Console::ReadLine()); //Parse =string to int
Console::WriteLine(S"{0}", n.ToString() ); //Convert int to string {0} spacing
//C++
int a[10];
int b[2] [3];
//C++.net
//Manged code allows for the compiler to do garbage collection
Int32 a[] = new Int32 [10];
Int32 b[,] = new Int32[2,3];
These are just few of the basic differences. The real value of .net comes in windows programming.