Crocs, are agresive, always
Caiman depend of mensures. The big one, black caiman is a furious and big predator (18 feets)
aligator is short repitile and eventualy atach, but is not common.
They are a diferents beens and diferent behaviors.

Big snake in florida is not american snakes (they are boa type, contrictor serpent like eunectis murinus - anaconda or python), they was a pet that became big, and people put free, they are really dangerous.