Fill in the Blanks Crocodiles vs alligatorsOnline version Click the correct word for each of word in bracket. by Yasmine Hidayah 1 Both crocodiles and alligators are reptiles . They ( fell ) fall in the same order of animals which is called Crocodylia . Crocodiles ( has ) longer , V - shaped heads while alligators have shorter and ( wide ) U - shaped heads . When a crocodile ( closed ) its mouth , its fourth tooth sticks out while alligator's doesn't . Crocodiles are also ( adapting ) to living in saltwater while alligators ( prefers ) freshwater lakes and marshes . Crocodiles are also ( most ) aggressive than alligators . Crocodiles can be found in the wild all over the world . ( Therefore ) , alligators in the wild are only ( find ) in China and in the US . The average lifespan of crocodiles ( are ) between 70 and 100 years while alligators ( living ) between 30 and 50 years . Fully - grown adult crocodiles are usually larger than adult alligators too .