Well, the first 3 are abelian: , so they can't be isomorphic with the non-abelian quaternion and dihedral groups.

Now, how these three aren't isomorphic between them? Easy: count number of elements. For example, has an element of order 8 and none of the other groups has such an element, and all the elements in the third group have order 2, but not all in the second one...

Tonio