What’s the difference between Co-operation and Co-opetition mode?
The Group Mode determines how enemies and loot scale for each player. In Co-operation mode, each player encounters enemies and loot that are scaled to their level. Loot drops are also instanced, meaning that they are unique for each player in this mode. Co-opetition uses the “Classic” Borderlands rules. Enemies and loot are scaled to the host player’s level, and loot drops are the same for all players (meaning that each item can only be picked up by one person).