Sorcerers differ on Athas a lot more than they do in any other setting. The word sorcerer is commonly identified with the Sorcerer-Kings who gained their powers through being taught by Rajaat. In other settings sorcerers have gained their powers through blood lines of powerful magical creatures such as dragons. Those sorcerers are foreign to the world of Athas, though no one can say for certain that they do not exist.
It is tough for magic users on Athas to be trained in wielding their power, without the assistance of the Veiled Alliance or Sorcerer-Kings. Many untrained arcane users are sorcerers, going on instinct without the use of spellbooks or pacts. Training may come later down the road, if they can survive being what they are in a world that despises magic.