Who Feeds the Church?
Those of the faithful who are consecrated by Holy Orders (bishops, priests and deacons) are appointed to feed the Church in Christ's name with the word and the grace of God (Lumen Gentium 11; Lumen Gentium 18-29; CCC-1536; John 21:15-17). In other words, Christ uses the clergy as His instruments to feed His people with the sacraments and the Gospel. When the clergy feed the Church by teaching the truths of the Gospel (Jesus), souls will be able to spot the lies taught by Satan. When the Church is fed through the sacraments, it is empowered to build up the Kingdom of God.
Below are some distinctions between bishops, priests and deacons:
It is concretely through the bishop that we have access to the sacramental life of the Church. He is the source of all authority in teaching and governing in the diocese that he heads. He is also the channel through which the grace of the sacraments in his diocese flows. This can be directly in that he ordains the priests in his diocese. It can also be indirectly that he regulates and oversees the Church’s entire liturgical life. This is especially true of the celebration of the Eucharist. Due to all of these facts the bishop is the visible link we have with the Church of Christ and it is through him that we have access to the life of the Church.The Eucharist: Life of the Church .
For more information on the role of the bishop, refer to Christus Dominus, Lumen Gentium 18-29, and Pastores Gregis.
"Because it is joined with the episcopal order the office of priests shares in the authority by which Christ himself builds up and sanctifies and rules his Body. Hence the priesthood of priests, while presupposing the sacraments of initiation, is nevertheless conferred by its own particular sacrament. Through that sacrament priests by the anointing of the Holy Spirit are signed with a special character and so are configured to Christ the priest in such a way that they are able to act in the person of Christ the head." (CCC-1563).
"Whilst not having the supreme degree of the pontifical office, and notwithstanding the fact that they depend on the bishops in the exercise of their own proper power, the priests are for all that associated with them by reason of their sacerdotal dignity; and in virtue of the Sacrament of Holy Orders, after the image of Christ, the supreme and eternal priest, they are consecrated in order to preach the Gospel and shepherd the faithful as well as to celebrate divine worship as true priests of the New Testament." (CCC-1564).
For more information on the role of the ordained priesthood, refer to Optatam Totius, Lumen Gentium 18-29, Catholic Priesthood Through the Ages, Pastores Dabo Vobis, Priests and Deacons Ministers of Mercy, and Presbyterorum Ordinis.
In Paragraph 1596 of the Catechism, the Church elaborates in greater detail about the Diaconate, telling us that deacons are not ministers ordained to the ministerial priesthood, but are ministers ordained to the task of service to the Church.
It is important to mention that there are differences between Roman Rite and Eastern Rite deacons. Roman Rite deacons are an ordinary minister of the Sacrament of Baptism (CCC-1256) and can assist at the celebration of a marriage. The Catechism tells us in Paragraph 1630 that when a Roman Rite deacon assists at the celebration of a marriage, he receives the consent of the spouses in the name of the Church and gives the spouses the blessing of the Church.
According to the traditions from Eastern Catholicism, Eastern Rite deacons are not an ordinary minister of the Sacrament of Baptism and can not assist at the celebration of a marriage. Eastern Rite deacons instead have been given more liturgical roles at Mass, while Roman Rite deacons have been given less liturgical roles at Mass. To learn more about the Diaconate, refer to Permanent Deacons-Question from Phil on 05-30-2004, Sacrum Diaconatus Ordinem, Priests and Deacons Ministers of Mercy, Lumen Gentium 18-29, The National Directory for the Formation, Ministry and Life of Permanent Deacons in the United States, CCE & CCL - Permanent Deacons, CHRIST THE SERVANT: THE VOCATION OF DEACONS - DVD, and The Faith Mystery of the Permanent Deacon.