What is the difference between “long”, “long long”, “long int”, and “long long int” in C++?

I am transitioning from Java to C++ and have some questions about the long data type. In Java, to hold an integer greater than 2³², you would simply write long x;. However, in C++, it seems that long is both a data type and a modifier.

There seems to be several ways to use long:

long x;
long long x;
long int x;
long long int x;

Also, it seems there are things such as:

long double x;

and so on.

What is the difference between all of these various data types, and do they all have the same purpose?