premise: A man in a sweatshirt places a garbage bag over a mailbox. hypothesis: The man wearing a garbage bag places a sweatshirt over a mailbox.
contradiction: The two sentences are different in that in sentence one the man is wearing a sweatshirt and in sentence two he is wearing a garbage bag. Their actions are slightly different as well, in sentence one he is placing a garbage bag on a mailbox whereas sentence two he is still placing something over a mailbox but this time it is a sweatshirt.