Everything hits harder and mechanics failures count more (if you don't hide behind a rock, you get one shot, etc), but A9S is probably the easiest raid floor since at least second coil so... not much? There are really only four people in the group that need to know the fight--the MT needs to know where to point the boss when, the OT and one healer need to know the power generator pick up, placement, and add kite spots, and the designated Alarum dude needs to know how to do the Alarums (tag thing, take to spot, kill thing.) If you're one of those four people and you don't know the role, it's rough. If you're one of the other four people, you're pretty much reacting to some obvious telegraphed tells, hiding behind the boss when he tank busters (which doesn't have the orange marker telling you anymore, but just get on the butt during Scrapline or the puddle during double scrap), following the group and just hoping the four people who need to know the fight know it.
9 is probably easier than Sophia EX to be honest since there's no randomness to the mechanics.