Skills
Novice - Lvl 1 - 10
Adept - Lvl 11- 25
Apprentice - Lvl 26 - 50
Journeyman - Lvl 51 - 75
Master - Lvl 76 - 100
Grandmaster - Lvl - 101+
Wizard Knowledge
Apprentice - Hogwarts age
Journeyman - Pursuing mastery
Master - Completed mastery in a field
Grand Master - Mastery in many subjects or deep knowledge in many. (Dumbledore, Unspeakables etc.)
Wizard Power
Average wizard
Above average (Novel Cedric Diggory, Viktor Krum)
Adept (Members of nobility of this book)
Elite (James Potter, Sirius Black)
Mage (Dumbledore, Voldemort)
Archimage (Merlin level)