The Cleric is a sub-class of Sorcerer, and is differentiated by the following attributes and restrictions:

Spells:
The Cleric opposes all undead especially, and will try to use Holy Bolt in any situation possible. The Cleric cannot use any "summoning" spells, and so is precluded from using Guardian, Golem, Elemental, Bloodstar, or Bone Spirit. All lightning-based spells are also forbidden, but all fire-based spells are allowed. Flash actually becomes a useful spell (at high level) against tougher hell opponents. These spell restrictions include scroll or staff based spells as well.

Weapons:
The Cleric may not use any edged weapons, or bows.

Equipment:
The Cleric cannot use any "darkness" items, but otherwise is not restricted in armor or jewelry.

Clerics take great pride in clearing out the first four levels of the game, and will try to do so as often as practical in gameplay. Clerics usually have some sort of suitably virtuous or honorable phrase hotkeyed as a warcry when slaying undead.