Flyff Arena PVP is where all players (above level 20) can have a free for all with anyone within the arena. There is no level requirement to who you kill, everyone can kill everyone. You can enter the arena via Flaris, Darkon, and Saint Morning.
Duel PVP can happen at any place, at any time. A player must right click the character they want to duel (they must be within 19 levels of each other) and send a request; if its accepted swords will appear over the killing target, and there will be a countdown. After the countdown, the players begin to fight; the winner gains 5 fame points, the loser loses 1.