A Roman Catholic Religious Order is a community of sisters, nuns, priests, brothers, or monks and often a combination of two or three of these. These communities are based on a rule or way of life that the founder felt obligated by God to live. For example, the Franciscan Order, one of the most well-known Orders, was founded by St. Francis in the 13th century. He founded his order on a rule that originally allowed its members no possessions, stability, or wealth in any manner (this Order, because of its extraordinary growth, now is allowed more stability and possessions but still demands a life of simplicity). There are hundreds if not thousands of different Religious Orders in the Catholic Church that all are founded on a unique rule or mission. After the extremely difficult decision to become a priest or Religious, the next and second most difficult decision is to find the Religious Order that suits you (unless, of course, you plan on becoming a diocesan priest). This web site can help you find information on several Religious Orders.
A Religious is any person that follows a rule in a community. There are several types of Religious, for instance: a brother, sister, monk, nun, priest. A secular priest differs from a religious priest. A secular priest is a priest that does not live a rule, meaning a diocescan priest while a Religious prist is one that follows a rule in the Religious Community that he has chosen. Catholic priests are unique in the fact that they are the only people that can administer confession (sacrament), say mass (transubstantiate the bread to Body, sacrament), give the Anointing of the sick (sacrament), and administer Holy Orders (even though that must be done by a Bishop or higher, but a Bishop is first a priest, sacrament). Although it varies on the Religious Order, all Religious take a vow of obedience (to all above him in the Church and to God), poverty (to have little or no personal possessions), celibacy (no spouse or sexual relations). Some Religious may take another vow that is unique to their Order and some Religious Orders may have some differences in these three vows. Diocesan priests do take vows of Obedience and Chastity but not a vow of poverty, they do however take a promise of simplicity.