Humans are the only mammal which is a habitual biped. Primates have eyes with overlapping fields of vision which permit them to see in 3 dimensions and with accurate depth perception. All primates have prehensile hands which is to say that we can hold objects in our hands as a fist or between fingers and thumb. Large complex brains. Human brains are larger and more complex than most mammals and all other living primates.
All animals communicate, but only humans do so through language.
Only humans have culture, that aspect of our lives which we learn and thus inherit from our ancestors.