Advanced Dungeons and Dragons Classes

The Priest Class

From the Players Handbook page 32

The priest is a believer and advocate of a god from some particular mythos. More than just a follower, he/she intercedes and acts on behalf of others, seeking to use his/her powers to advance the beliefs of his/her mythos. All priests have certain powers: The ability to cast spells, the strength of arm to defend their beliefs, and special,  deity granted powers to aid them in their calling( i.e. Turning the Undead).

All priest spells are divided into different spheres of influence, and these are: All, Animal, Astral, Combat, Charm, Creation, Divination, Elemental, Guardian, Healing, Necromantic, Plant, Protection, Summoning, Sun, and Weather.

The Cleric:The most common of the priest class is the cleric. The cleric may be adherent of any religion (though if the DM designs a specific mythos, the clerics abilities and spells may be changed). Clerics are generally good, but they are not restricted to good; they can have any alignment acceptable to their order. A cleric must have a Wisdom score of 9 or more. High Constitution and Charisma are also particularly useful. Those with a Wisdom score of 16 or higher gain a 10% bonus to their experience points gained.
Clerics are sturdy soldiers, although their selection of weapons are limited (to that of their specific mythos). They can wear any type of armor and use any shield. Standard clerics are very reluctant to shed blood or spread violence, are allowed to use only blunt or bludgeoning weapons. This is kind of a double standard for clerics, because while sharp edged weapons shed blood, their counterparts (the blunt weapons) will cause the most violent trauma available.
The cleric receives his spells as insight directly from his/her deity, as a sign of and reward for his/her faith, So he/she must take care not to abuse his/her power lest it be taken away as punishment.

The Druid:The druid is an example of a priest designed for a specific mythos. His/Her powers and beliefs are different from those of the cleric. The druid is a priest of nature and guardian of the wilderness, be it forest, plains, or jungle.
The druid must be Human or 1/2 Elvin. He/She must have a Wisdom score of at least 12 and a Charisma score of 15 or more. Both are prime Requisites. Unlike the cleric, the druid is only allowed to use "natural" armors, ie. leather armor, wooden shield, etc. His/Her weapons are restricted to those that can be made in the wilderness, ie. club, sickle, dart, spear, dagger, scimitar, sling, and staff. Both of these restrictions include the magical versions of them.
Druids do not have the same access to magic as the cleric. They have major access to the following spheres: All, Animal, Elemental, Healing, Plant, and Weather. They have minor access (magic levels 1,2,3) to the Divination sphere. They can use any magic items allowed to the priest with the exception of anything written (books & scrolls), and any weapons & armor not allowed by the druid class.

For more info on the Priest, pick up The Players Handbook.