You can hop on one leg. If you've lost one shoe and don't want your bare foot to touch the ground, you have to hop on one leg. 'Hop' can also mean a very short jump with your legs together (as opposed to a 'leap', for example, which is a very long step with the legs apart). Kangaroos hop. Skipping is a light jumping way of moving.You lift your legs higher than with walking, and your whole body bounces up and down. Small children - especially little girls - tend to skip along when they walk, particularly when they're happy. It also helps them keep up with adults, as skipping is faster than walking (but slower than running). You can also 'skip' with a rope, as a child's game or as exercise, either on the spot or moving along.

I can visualize the difference but I'm not sure I can properly explain it. I'll try, though. A skip looks like a combination of walking and jumping. A person who is skipping is jumping a little bit with each step (s)he takes. A hop is where a person takes a small jump forward with both legs. That's the only form of motion; there is no walking or stepping involved like there is in skipping. Hopefully that makes sense.