Adult humans, who weigh only a little more than adult chimps, nevertheless have brains three to four times more massive. A human infant a few months old already has a larger brain than a grownup chimpanzee. It seems very likely that we are significantly smarter than the chimps because we have a significantly larger brain - despite the comparable body weights. But the human brain isn't entirely a proportional scaling up of a chimp brain. Significantly, some of it seems to be related to speech.
Primates have five individual toes.
All primates, except humans, have a big toe that is positioned on the side of the foot. In this position, the big toe can act in a way similar to a thumb. The foot can grasp objects, such as branches and food. The foot can even hold an orange. Humans on the other hand cannot use their feet for grasping objects.