What is the difference between a diocesan (or parish) priest and a priest from a religious order?
By Fr. Arthur Carrillo, CP
The easiest way to understand the difference is to begin with the diocesan priest. He is ordained for service to the diocese, and the diocesan bishop has the authority to manage his assignments from parish to parish, or job to job (e.g., chaplain, teacher, office worker for the diocesan offices). In a manner of speaking, he "belongs" to the diocese. In most cases, the diocesan priest lives at the parish rectory and not in a religious community, unless he is part of a religious community.
A religious priest is one who joined a religious community with the intention of later being ordained to the priesthood. "Joining a religious community" means learning to live with the spiritual traditions and practices of the religious community, the Passionists, for example. This usually happens through a period called "initial formation," and is marked by a "novitiate," which is completed by the profession of "vows," the promises that bind the individual to the authority of the religious community (usually expressed in "Constitutions and Regulations"). All of these steps must be completed before the individual can proceed to receive Holy Orders (Diaconate and Priesthood).
For the religious priest, his obedience is to his superiors in the religious community. If the religious community has been invited to staff a diocesan parish, he may serve for some years in such a parish. In that case, he would have two separate superiors during his parish assignment. He must obey his religious community superior in matters of religious community life, and he must follow the authority of the diocesan bishop in matters that have to do with the operation of the parish to which he has been assigned by the religious superior and accepted by the diocesan bishop.