Well it looks like i'm going to be in the minority by saying i think it was a poor question. I got it wrong because I was expecting, funny enough, a question on identity. The fact that the word identity doesn't appear anywhere in the explanation of the answer backs my opinion up that this was a sort of trick question. I have no problem with testing on the differences between temp tables and table variables and indeed, if the question had said it was related to that i would have got it right.
Sour grapes maybe, but I think questions should be about testing someone's knowledge, not their powers of observation.