If you a team leader, you can choose a type of XP distribution in your team: Shared XP or Distributed XP.
Shared XP In this case all earned XP will be equally distributed among all players, regardless of their levels.
Distributed XP In this case XP is distributed accordng to the damage made. So the more damage you cause to the target (monster, chess stone, etc), the more XP you will get.
Players are normally prefer Shared XP, as low-level players can get more XP. IMHO Distributed XP mode is fairer because it gives XP according to your input.