x ball is a 5 man format with sideline coaching and 45 minute games in which you have to hang the flag up to 7 times with 2 minute break between each point.... they also use a 12.5 bps ramp the games can be like 45 seconds long or 10 minutes and it is intense
X-ball is a forum of speedball. they call it speedball because of it's fast pace. the reason "sup air" fields evolved to "X-ball" is purely for spectator viewing pleasure. There is a literal X in the middle of the field(out door fields tend to use a half X) that is designed to push players to the sides to play that way spectators could see more action.
There are a bunch of different leauges that use X-ball, all with different rules. Sean told you the majority of them.