If Carlsen played only very complex positions against Aronian then maybe their personal score would be more in favor of Aronian. Even so would Aronian out score Magnus? We can't say.
If Aronian only played very simple positions against Carlsen then maybe their personal score would be more in favor of Carlsen.
When you have different tastes than your opponent, you never completely get what you want. In the opening the two players meet somewhere in the middle. In this spectrum of positions, Carlsen > Aronian.
And more importantly, against the other top players in the world, Carlsen outperforms the others.
Karpov said when he was world champion that the world champion just does everything a little bit better. It's probably fair to say Carlsen's a little better in the middlegame and endgame. He probably sees a little more tactics and his calculation is probably a little better too.
I think maybe it's fair to say all players like certain kinds of positions better than other kinds, and a stronger player is often more successful than his opponent at steering the game toward those kinds of positions, while simultaneously making sure he doesn't worsen his position (or even improves it) in doing so.
To anyone who wants to answer the OP : check out first his threads asking the same question, for instance
http://www.chess.com/forum/view/general/the-problem-with-chess-is-its-incosistency