Sorcerers vs. Wizards?

Something caught our eye about the definition of a sorcerer verses a wizard, albeit in a D&D setting:

Sorcerers are arcane spellcasters who manipulate magic energy with imagination and talent rather than studious discipline. They have no books, no mentors, no theories just raw power that they direct at will. Sorcerers know fewer spells than wizards do and acquire them more slowly, but they can cast individual spells more often and have no need to prepare their incantations ahead of time. Also unlike wizards, sorcerers cannot specialize in a school of magic. Since sorcerers gain their powers without undergoing the years of rigorous study that wizards go through, they have more time to learn fighting skills and are proficient with simple weapons.

Okay, so Warren Windrow was antagonist of The Spell of the Sorcerer’s Skull and Zebulon Windrow was the arch-fiend in The Revenge of the Wizard’s Ghost – so the above verbiage makes Zebulon more powerful than his relative, Warren...?  Right?