stronger but smaller then others

You have poorly defined what you mean by bigger and/or stronger about them so it's hard to answer you accurately. My guess is that they're not the same height as you nor have the same physical dimensions. It's not about the size of muscles.

Muscle strength is not only about the mass of the muscle - it's also about the elasticity of the muscle and the explosive fast-twitch vs. slow-twitch fibers (instant response) quality. How are you determining the strength comparison?

There are many compact but strong athletes. The recently-deceased fitness guru Jack LaLanne was very strong but smaller (5ft 6in or 1.67 m) build, too.

those that use then are more likely to have stonger muscles from the neck down than those that use than

This guy doesn't seem to mind if he's smaller than others...