The governing rulers of the Light side is the Wizard Clan, and on the Dark side, respectively, the sorcerers.
The Wizard Clan wears red robes of all styles and varying shades of red, carry hand-carved wands, and do not have to recite spells when performing magic if their skill is high enough. The Wizards' council governs that of the Light side, and maintains peace on said side.
The Sorcerer Clan wears blue robes of all styles and varying shades of blue, carry long staves, and must recite spells when performing magic. The Dark side is rather difficult to maintain order in, as the Lurkers, Summoners, and Magicians do whatever the hell they want. The Sorcerer Clan, however, is mainly represented on the Neutral council, which is a combination of Light and Dark side leaders.
It is suggested that the restrictions on the Sorcerer Clan were actually caused by the Wizard Clan; A common folk tale of the Seers regards the Wizards and Sorcerers as one Clan in the distant past, the "Magic Wielders" or something similar. Sorcerers incline to staves, as they can be used as a sort of mace like weapon. Sorcerers also are likely to delve deep into the dark arts. Legend has it, the "Wizards" half of said combination clan cast a curse upon all Sorcerers, deeming them to carry heavy staves with their magic locked into orbs, and to make them recite spells aloud so that a defence spell would be easier to conjure. Whether this old Seers' tale is true or not will never be known, but to this day the Wizards and Sorcerers remain mortal enemies.

me @ me: talk about Lurkers!
EDIT: wait there's also Grounders and the floating head, or the abandoned citadel and the Coatyl