Well they have lots of uses, but wrecked can be used like "a car wreckage". The car is destroyed (wrecked) after the person driving the car crashes their car (gets into an accident). accident = do something wrong by mistake. wreck = to destroy wreckage = something that is destroyed hope that helps, if not I'll try again.

just to add to the other answer, wreck, used as a noun would mean what is left over after the accident. Look at that wreck along side the road!

They're the same, but: all wrecks are accidents, however not all accidents are wrecks. (this happens a lot in English :-) ) As McKauley says, a car wreck is an accident in which a car was wrecked (destroyed); it can be called an "accident," but an accident can can also be bumping into someone or stepping on their foot, or even telling a friend someone else's personal business & then remembering that that friend didn't want you to share it with anyone. :-O