All Christians, as a consequence of their baptism, have a call, a vocation to follow Christ and to make Christ and his Gospel - his Good News - present in the world. Every Christian, in imitation of Jesus, is to strive by word and example to proclaim and bring about the reign of God, God’s kingdom in the world.
Vatican II recognised that all who are baptised participate in the priesthood of Christ, but confirmed Catholic tradition on the clerical hierarchy by decreeing that there is a distinction between the priesthood conferred by baptism and that conferred by ordination. The ordained priesthood has three orders: bishops, priests, and deacons. The Council was very clear in affirming baptism as the sacrament of ministry with lay ministry and ordained ministry as ways of living out that baptismal commitment. Together, lay and ordained have shared responsibility for the work of the gospel, in social justice and human rights.
The context in which this baptismal call is lived, is related to what is called in church language ‘one’s state in life’. Within the Catholic Church, there are two basic ‘states in life’, namely, the lay state and the clerical state. Those in the lay state can be further divided into married laity, unmarried laity and members of religious institutes. The clerical state comprises those ordained - whether deacons, priests, or bishops. Those in the clerical state may be either secular clergy or members of religious orders.
Religious life was born in the East during the first centuries of Christianity. Public profession of vows of poverty, chastity and obedience distinguish religious life. Through these vows, religious solemnly bind themselves to the following of Christ, to communal membership of a religious institute and to a particular apostolate or work within the Church and society in line with the characteristic charism, spirit and tradition of the group of religious to which they belong. Religious are committed to a celibate life, normally lived in community, to obedience to the Church and their religious superiors and to a simple life lived in imitation of a poor Christ who emptied himself for the sake of others. Religious institutes collaborate with church authorities, such as the diocesan bishop, in the pastoral work of the Church. Such collaboration may take place in relation to education, healing ministry, or leadership and support for the life of Church communities, missionary outreach, promotion of justice and peace. Whatever the apostolic work of religious, a crucial dimension of their life as religious is in giving witness to a life committed to prayer and union with Christ and expressed in selfless service of others. Religious life witnesses to the beauty and challenge of a life totally committed to God in imitation of Jesus Christ.
By tradition, the ordained clergy (bishops, priests, and deacons) are distinguished from the laity who assist in the ministry of the church. Some Catholics live together in Religious Orders, serving the church and the world under vows of poverty, chastity, and obedience. Members of these religious orders or congregations include sisters (or Nuns), brothers (or Monks), and priests. Priests who belong to religious orders are sometimes called regular clergy, because they live according to a rule (Latin regula). Most priests, however, are ordained for ministry in a diocese under a bishop and are called diocesan or secular priests.
https://catholicidentity.bne.catholic.edu.au/scripture/SitePages/Vocation-The-christian-call.aspx