Experience (XP/Exp) is required to level up your character. Experience is gained by defeating enemies or completing missions, and varies based on the enemy level or difficulty of mission.
Requirements to Level:
Reputation (Rep) is used to increase your rank within Factions. Reputation is gained by completing specific missions and will allow users to gain access to items in the faction shops as they rank up. Daily missions will give more rep than other missions, and can be done once a day.