A lot of you guys are saying things about intelligence, culture, empathy and things like that, but fundamentally it all comes down to the same thing.
Humans have the largest brain, proportionate to their body, of any organism on the planet. This allows us to communicate in more complex ways, solve problems with more creativity/success and theorize on matters which do not necessarily affect us in a direct way.
Other animals are incapable of performing at the same standard of these activities as we are, but are specialised in other ways, usually with increased sensory development e.g. a dog's nose, an eagle's sight and a bat's echo location.