*WARNING* CONTAINS MINOR SPOILERS
No Rank - 0% Level exp - Nothing special so no reward
Ordinary - 10% level exp - (Just shows as quest in the description) - a standard quest
Rare - 25% level exp - slightly harder than ordinary but still solo-able
Epic - 50% level exp - recommended you take a group
Hidden - 150% level exp - Can be any of the other types of quest's but only shows up after you have completed all or part of it.
Unique - 100% level exp - a unique quest that only appears once and there never appears again whether you complete it or fail it.
Atlantia Unique - 100% level exp - a unique quest that needs to be completed in the real world and only appears once and there never appears again whether you complete it or fail it.
Genesis World - 200% level exp - a quest that effects the whole Genesis world
Atlantia World - 200% level exp - a quest that effects the whole real world of Atlantia