The main difference between Overpronation and Underpronation is the rotation of the ankle of a waling person. In overpronation your ankle rolls extra inward than regular while you are taking a step during running or walking. Typically, people who overpronate are extra liable to traces of their massive toe and 2nd toe, because the inward rolling forces weight onto them. While in Underpronation the foot is rolled outward while on foot or running, and reasons the little feet and outer fringe of the foot to do the work. In a few cases, individuals who underpronate may also have excessive arches.