exactly. i don't know but now i no
The difference is the pairing and time frame.
With Swiss you play a tournament with a predefined amount of rounds. With each round, everyone waits untill the last games finishes. Then a new round starts where the players are paired by the Swiss system.
With arena there is a time frame for the whole tournament, let's say 2 hours. In this to hours you get paired to who ever is ready to play when you finished your game. Everyone has the same time limit but when you finished a game, you get paired directly again to someone who is ready too. In this case, nobody waits till a round has finished. Everyone just plays.
So if you play short games, you get to play more than someone who plays long games. In one long game of a another player, you can play 4 short games ending up with more points.
At the end of the tournament time of 2 hours, every game stops and the winner is the one with the most points. So everyone plays a different amount of games.
I hope this clears it up for you.
What's the difference between Arena and Swiss?