Difference between a diocesan priest and a religious priest?

A diocesan priest

A diocesan priest ordinarily serves the Church within a well-defined geographical area (a diocese). He usually serves the people within that particular diocese as a parish priest, but may also be involved in other forms of ministry: teaching, chaplainry in hospitals or prisons, campus ministry, etc. Most diocesan priests live and work in the same diocese for most of their life. Diocesan priests make two promises: obedience to the bishop and celibacy. This means that they promise to work with the Bishop and do what he asks of them for the sake of the people of the diocese. The promise of celibacy is both a sign of the priest's interior dedication to Christ and a sign of an undivided heart to serve the people of God.

A religious priest

A religious on the other hand, is a member of a community that goes beyond the geographical limits of any diocese. A religious priest seeks to live a vowed life within a community of men for mutual support and the accomplishment of some work. An emphasis in the community is on shared ideals, prayer, and commitment to Christ. Religious priests work in a wide variety of ministries. Religious communities were founded at different times in history and often focus on a special ministry. As members of a worldwide order or group of men, following the ideals of their founder (e.g., the Benedictines follow the Rule of Saint Benedict), they make vows to live their lives in the same manner.

Unlike a diocesan priest, who makes a promise to his bishop, religious priests take vows of poverty, celibacy (chastity), and obedience that bind him to the community.