Human can think and have a soul. Robots just do commands and obey to what Humans say. Even if they are smart when they die they are not alive anymore.
Also Humans can eat. Robots just get oiled up, and charged like a battery.
Also if they try to hurt us they could slice through us like diamonds but all humans can do is abuse while robots can harm innocent people. (Law#1 A robot is not allowed to hurt another human being Law#2 A robot can obey a direct order if not conflicting with the first law Law#3 A robot can defend itself if not conflicting the first or second law).
We ask questions, and we think while a robot could not be here on Yahoo answers unless a human told it too.
Now that should explain the differences between a robot and a human.
A robot can't love, cry, get angry, and throw temper tantrums while a human does.