Artificial Intelligence (AI) describes computational system with intelligent/complex behaviour suitable for achieving goals. While AI can be entirely software, robots are subject to physical impact, typically through 'sensors'. They exert physical force, usually through 'actuators' like a gripper or a turning wheel. Autonomous cars/aircrafts are robots. Only a tiny portion of robots is humanoid like you see in the movies. Some robots use AI while others do not. AI's main purposes include sensing, planning, etc. Its applications include perception, analysis, natural language processing, so on and so forth.