There are simple key differences between Chaos and Order. The Chaos Faction is centered around higher damage and blunt heavy attacks that damage a group of monsters and casting certain types of effects like poison and blind. The Order Faction is focused on "lighter" attacks that do very well against monsters and often stack damage. If you choose the chaos faction, be ready for your class to probabaly train slower than your order counterpart but do more damage so to say to make up for it. If you're going order, you probabaly train faster than the chaos counterparts, but deal weaker damage.