Groups of men or women who live under a religious rule and who publicly profess vows of poverty, chastity, and obedience form a religious community. They are referred to as an order or congregation who are recognized by Church authority. Religious communities typically follow the rule of their founder, which can be apostolic and characterized by working in the world, or contemplative, which is characterized by a life of solitude and prayer. One way to identify an individual’s connection to a specific order or congregation is by the initials following their name, which identifies the order to which they belong.
A vow is a public sacred promise or commitment made to God with the approval of the Church. The vows of poverty, chastity, and obedience are also known as evangelical counsels; they may be taken for one, two, or three years, depending upon the decision of the community and the individual. These promises are renewable for up to nine years. As soon as three years after making temporary vows, a person can make a promise to live the vows for life.
A Catholic Nun is a woman who lives a contemplative life in a monastery which is usually cloistered (or enclosed) or semi-cloistered. Her ministry and prayer life is centered within and around the monastery for the good of the world. She professes the perpetual solemn vows; living a life according to the evangelical counsels of poverty, celibacy, and obedience. Check out the Carmelite Nuns of Baltimore for example.
A Catholic Sister is a woman who lives, ministers, and prays within the world. A sister's life is often called "active" or "apostolic" because she is engaged in the works of mercy and other ministries that take the Gospel to others where they are. She professes perpetual simple vows living a life according to the evangelical counsels of poverty, celibacy, and obedience. Check out the IHM Sisters of Monroe, Michigan for example.
A Brother is a single, Catholic layman who lives his baptismal commitment by joining a religious community of vowed members dedicated to serving God and those around them. Religious brothers profess the evangelical counsels (vows) of poverty, chastity, and obedience. They also commit themselves to a life of ministry, prayer, and Gospel witness within the context of community. The difference between a brother and a priest is the Sacrament of Holy Orders. The term “Religious” refers to the fact that a man is consecrated by vows of poverty, chastity, and obedience, and living in a religious community. From that community of consecrated men, some are chosen to receive the Sacrament of Holy Orders in order to provide the sacraments for the others.