What wins Three of a kind or three pair?

3 pair does not constitute a legal hand in poker. Therefore, 3 of a kind is better. You play your two highest pairs if you so happen to have 3 pairs in play!

For instance in Texas Hold em: You have a Pair of Queens, other dude has Jack ten. The flop comes out and its Jack 10 Ace then turn is ACE and River is 3. The guy who had 2 pair Jacks and tens loses because Queens & Aces is higher than jacks ACEs.