The mage - From the word [i]Magus[/i], a mage is not one necessarily born of magic, but is inaugurated into it by studying, experience and learning. A mage's power is a direct reflection of those attributes.

The Wizard - Derived from the word wisdom or wise, the wizard is often born intimately aware of the flow of magic. A wizard gathers power through knowledge, generally recorded for memory in items like spell books. 

The sorcerer - A sorcerer is considered a weaver of fate, and intuitively casts spells, unlike a wizard whom's power is his memory. This class of magic user is perhaps the most ambiguous in terms of how their powers really operate.

My character Corban/Corellian is part sorcerer, part mage in his ability to intuitively cast spells, but all spells cast are based on his intimate understanding of the power which he wields(study and learning) and the natUral world around him.