Even in that, I can see differences.
Summoners: gaining assistance, guidance, protection, defense, attack, etc. by employing external sources
Abjurers: defense, protection, warding
Diviners/Prognosticators: finding out the past, present and/or future using interpretive practices
Druids: communicating with, connecting to and gaining favor with nature
Archmages: leadership, guidance, defense and protection
Sorcerers/Sorceresses: darker means; deception, social/situational manipulation, employing dark entities (please disregard modern sources)
Wizards: learning and dealing with everyday life; think Merlin from The Sword in the Stone (he's like a teacher and adviser)
Witches: dealing with everyday life (helping self/others, hurting others, etc), governed by their alignment
Enchanters/Enchantresses: seductive deception, charm and cunning (likely Hypnotism or Persuasion)
Puppeteer: sheer control; no need to attack when you can simply force others to do it for you
Hags/Crones: dealing with everyday life (helping self/others, hurting others, etc), guidance, etc, governed by their alignment
Warlocks: harming others, or helping them with their OWN purposes in mind
Necromancer: learning and advancing...um...less than moral objectives (using the dead, as the name implies)
Apprentices (of any mage); to learn (duh), and take on the same agenda as their master
Zealot: understanding, control (even mimicry) of one element of nature considered to be more powerful than the others
Wiccan: helping self and others by natural means
Mystics: following occult ways of doing things (arcane versions of any of the above mages)
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)