There are a number of quest (a little over 36,000 right now) to be fulfilled in CA ranging from easy to insane, music to all out gun fight, and rpg to stand alone. The ranks of each difficulty of a quest depends on what the level status in that category is.
Recruit
These are the easiest of all the quests, and the ranks of this difficulty is from 1-8.
Easy
These are the second easiest quests in the game, and there scale runs from 1-8.
Novice
These quests typically take from 20-35 minutes to go through and their scale rates from 1-9.
Normal
Quest of these level are fairly easy in the factor that they can involve some difficult puzzles and searches, but the battles tend to stick to pretty easy. With these scaling from 1-8.
Apprentice
These are preferred for the players who are around level 150-200, and so if you want a challenge for your first 300 starter levels, then go on ahead with these adventures. Scale from 1-8.
Average
These quests are the average challenging ones that involve spending up to a hour and 35 minutes and rate on scale of 1-7.
Hard
These quests tend to be a very difficult task for the some of the most skilled level
Heroic
Bravery
Master
Legendary
Warmaster
These are the hardest quests offered to the F2P players and they scale from 1-3.
Legend of the Claw
These are the legends of all of the quests, and the Legend of the Claw scale sets at 1-3.