A Diocesan Priest ordinarily serves the church within a geographic area called a Diocese. He ordinarily serves the people as a parish priest, but he may also be involved in many other forms of ministry like teaching, hospital ministry, campus ministry, or prison ministry. Diocesan priests make promises of celibacy as well as obedience and respect to their bishop. They do not make a vow of poverty but are to live simply so they can be of service to God’s people.
A Religious Priest is a member of a religious congregation whose ministry goes beyond the geographic limits of any diocese. A religious priest seeks to live a life of poverty, chastity, and obedience within a community of men. The community shares a common vision and spirituality and often emphasizes a particular type of ministry.