there are a few diffferences. as Assassin mentioned you don't respawn on death until you reach a checkpoint (I.E. beating the oracles, beating the templar, etc). obviously the main difference is that the enemies inside of the vault are all level 30. the "protect the confluxes" stage is pretty much the same just harder enemies. the "destroy the oracles" part is the same just with harder enemies (but there is a way to do that entire part using snipers instead of dropping down into the templar arena). the Templar battle on hard mode is pretty much the same except that he puts the Detain field around more players than he does in normal. methods for beating him on hard vary a lot depending on your teams loadouts. gorgons labyrinth has a few additional gorgons to worry about. they aren't any more receptive or anything like that. killing the gatekeepers is just a bit more difficult cuz everything is stronger. fighting Atheon is the kicker in this whole thing.. first of all. the fact that he randomly teleports 3 people can be devastating if you have too many level 29s in your team but it isn't impossible to do it as a level 29. the "venus" side (right side, green area, whatever you prefer to call it) has a very strong praetorian that will wreck a level 29 if they take the relic. methods for fighting him are to always send a level 30. have the non-relic holders fire a volley of rockets to help out the relic holder. throw flashbangs at him to prevent him from hitting the relic holder. and a few others that are just preference. the "mars" side (left side, red area) has those 3 hobgoblins but at level 30 they will 3 shot a level 30. 2 shot a level 29. As for the people outside, 90% of the time all 3 of them will get detained when the other 3 get teleported. sometimes one person won't and there have been a few instances where someone that got teleported will also get detained so be prepared for anything.