Specialty priest

A specialty priest was a special kind of priest of a deity.

Difference from other Clerics
Specialty priests and clerics were similar in the sense both were practitioners of divine magic. The difference lay in their level of dedication to one deity. A cleric supported a cause or an entire pantheon, possibly praising one member of the pantheon above the rest or maybe even disagreeing with the rest, whereas a specialty priest was a follower of only one specific deity.

Differences in Powers
The options for powers possessed by every cleric was very varied. This was because the cleric was offered a huge variety of powers from every member of his pantheon. A specialty priest was limited in his choices even to the point of forfeiting some, like the ability to turn undead. In return, a specialty priest gained specific powers from his specific deity, which starkly differed from those of a standard cleric.

Difference in Reception
A cleric was—at least in theory—respected and liked by the entire pantheon, both by its members and priests thereof, except by those members of an opposing pantheon. A specialty priest on the other hand was poorly received by other members of the pantheon of the deity he or she worshiped, and by their followers, although of course exceptions existed.