To the compiler, they have exactly the same meaning.
Stylistically, there are arguments for and against both.
One argument is that the first version is preferable because the second version:
int* x, y, z;
implies that x, y and z are all pointers, which they are not (only x is).
The first version does not have this problem:
int *x, y, z;
In other words, since the * binds to the variable name and not the type, it makes sense to place it right next to the variable name.
The counter-argument is that one shouldn't mix pointer and non-pointer type in the same declaration. If you don't, the above argument doesn't apply and it makes sense to place the * right next to int because it's part of the type.
Whichever school of thought you decide to subscribe to, you'll encounter both styles in the wild, and more (some people write int * x).
