In both alligators and crocodiles, the fourth tooth on either side of the lower jaw is exceptionally long. When an alligator closes its mouth, those long teeth slip into sockets in the upper jaw and disappear. When a crocodile closes its mouth, the long teeth remain visible, protruding outside the upper jaw. In general, if you can still see a lot of teeth even when the animal's mouth is closed, you are looking at a crocodile. Alligators have plenty of teeth, but fewer show until the mouth is open.
Like sharks, crocodilians never run out of teeth, for sharp new ones grow in as old dull ones are shed throughout the animals' lives. Numerous as they are, crocodilian teeth serve only for grasping, not chewing. These animals gulp their food in large chunks and rely on powerful stomach acids to break it down.
Alligators and crocodiles both have thick, bumpy skin but alligators tend to be darker in color. Adult alligators are grayish black while adult crocodiles are light tan to brown in color. Young alligators can be more colorful with yellow or white highlights on a black body.
Another difference between crocodiles and alligators is their choice of homes. Alligators are freshwater reptiles, favoring the rivers, lakes, swamps, and marshes...