Ok, I will be more specific:
At the start, you can pick from one or two players, one is basically your same typical game, but if Two Player is chosen, you can control two people on the main map. After a fight in normal, you would be in the same spot, but in two player, the 2nd player would be where he was at before the battle started. On normal, when you walk around you can run into a battle, on Two Player, both can run into monsters if they walk around, not just main player (P1).