Well there are lots of diferent versions, as already demonstrated. Theres is no right or wrong set, so I'll give a few:
D&D 3rd edition:
Wizard: Trains and nurtures minor ability untill they can be quite efective(all spells know few spells/Day
Sorcerer: Lucks out on lots of talent, but tends not to train to hard, leading to a diferent but equal power level of a wizard (High spells/Day low Spells known)
Warlock: Warlock? whats a warlock? (they dont exisit)
D&D 4th edition:
Wizard: Wields arcane magic thru skill or talent
Warlock: Pact with Daemons, Stars (Yes I dont get it either) or Fey
Scorcerer: See warlock above.
D&D second edition (As I remember it)
They are all words for the same thing, but are generaly used to refer to diferent styles of magec:
Scorcerer: Lots of somoning and controling spells, ie "you, do it for me".
Wizard: Generic term for spellcaster, A balenced repituare of spells
Warlock: Firey death!!!
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