The level system:
The level system determines your status in the guild. Your status will determine what types of Missions you can accomplish, and what level of power you posses. The higher the level, the more chances you will be approved of doing a higher level job.
Your level is measured by the amount of posts you make in the guild, the number of members you defeat in duels, and the number of missions you accomplish. The more of these you have, the higher your status will be. Those who posses great strength will be given S-level status. These S-levels can then take S-level missions that give off higher rewards. If you want an idea of how the system works, read
Fairy TailMember= Members can take any of the jobs in the jobs post. They are not limited by the level of the mission.
Crew= Once you impress the Captains, you can ask them to do S-level missions. If you pass their trial, then you will be recognized as an S-level member. S-level missions are much more difficult, and have higher rewards.
Vice Captain= There are only 10 Vice Captains allowed. These Vice Captains are known as the 10 Great Holy Mages. These mages are recognized as the strongest mages in the guild. These mages are in control of the guild and can do whatever they like. They can also accept jobs and whatnot's.