Human: I'd like to know the difference between an alligator and a crocodile. Assistant: 
The main difference between an alligator and a crocodile is size. Alligators typically grow up to 13 feet in length while crocodiles can reach lengths of over 20 feet. Another key difference is that alligators have more rounded snouts and shorter, stouter bodies than crocodiles. Crocodilians are also known as “living fossils” due to their ancient lineage.