To the best of my knowledge, which should always be reviewed by others for verification, a priest can be a diocesan or religious priest. A brother is a man in a religious community, but not a priest. A monk is a type of religious man as are friars and canons. By “religious man” I mean a man in a specific community that follows certain rules and such and such.
The groups are best understood as sub-groups rather than separate groups, although there are some that try to break from the whole. These sub-groups can be divided in different ways. One way is by how they live, as traditionally monks did not live in the exact same manner a friar might. Another is vocation; some people are priests, and some are not. Some have a calling to preach, to help the poor, the sick, etc. Different communities may also be identified by how they feel most comfortable in reaching the goal. For example, Dominicans devote themselves to preaching and all who belong to their sub-group in some way contribute to preaching. All these groups, despite differences, maintain a core belief and faith in the Church.
Priests may receive income, as it were, based on what they do and their community. Diocesan priests receive a stipend, from what I understand, and are always at the service for their diocese. They do not take a vow of poverty because there are situations where they might have to own property. Religious priests, here used in the same manner as religious man, may have a vow of poverty, but that doesn’t mean they receive no support from their community.
There are basically two types of priests: Diocesan and Religious. Diocesan priests study at a seminary run by a diocese, and primarily work in and for a diocese. They take an oath of obedience to the Ordinary, as do all priests, but in this case it is the Bishop of their Diocese. They may have a flavor similar to religious priests, but perhaps not so. These men are usually what people think of when they imagine a priest. Religious priests belong to a specific community, like the Dominicans, and specialize in whatever their community does best. They can do anything a diocesan priest can, except maybe own things. When diocesan priests are unavailable, a bishop may request the aid of religious priests to man parishes. A religious priest may be a missionary, teacher, or a host of other things that a diocesan priest may not be able to do due to his duties at a parish. The bare requirements to become a priest are met regardless of type. Uh, did it make sense? Anyone want to back or correct me?
