Trials = For the competitive/Skilled players more at risk when you lose but better guaranteed rewards, it also takes less time (got flawless on my warlock and hunter this week/Last week) and it's usually takes about 90 max. Iron banner = more casual crowd with the skilled/Competitive players mixed in, rewards in the end are lackluster compared to the price you have to pay. Weapons you obtain aren't completely OP (excluding Felwinter, Jolders, and Radagas Fury) depends on the roll. IN can be very fun and relaxed you get to have 6 friends together and dominate (or not) but it's more casual because even when you lose you are rewarded and the level disadvantage isn't noticeable at all unlike in trials