There have been three main offices of the Church: Deacon, Priest, and Bishop. We will go through each one as the ministry is different for each one.
A deacon is a person that is ordained into the diaconate. The word deacon comes from a Greek word that means servant. In the book of Acts, we read that the Apostles would appoint deacons as a helping hand to the Apostles (Acts 6). We see deacons like Stephen, Lydia, and Phoebe in the Bible as examples of what a deacon is what are they are not. A deacon would help to care for the widows and others that society would look down upon and not even look at in that time. For this reason, a deacon is a servant to the people and is ordained to be in the midst of the people. This is why, today, during mass you see a deacon (if there is one in the parish) bring the Gospel into the middle of the congregation. It symbolizes that a deacon brings the Gospel to the people. A deacon is not only a servant of the people, but of the Bishop. The deacon assists the Bishop in the life of the Church and helps just as the deacons in the New Testament helped the Apostles.
A priest is a person that is ordained into the priesthood. A priest is a person that has been chosen to be the representative of the Bishop, and therefore Christ. A priest administers the sacraments by blessing the people and consecrating the elements in the Holy Eucharist. A priest hears confessions, celebrates the Eucharist, gives last rites, performs marriages, baptizes and is a pastor to the people. This office is an extension of the office of the Bishop.
A Bishop is a person that is consecrated into the episcopacy. A bishop as Paul describes to Timothy is an overseer. Tradition teaches that the Apostles handed their authority down to the Bishops and so Bishops are the heirs of the Apostles. So, Bishops are in Apostolic Succession. Bishops have the same ministry as a priest because a priest’s ministry comes from the office of the Bishop. In fact, all ministry comes from the Bishop. However, a Bishop also ordains Priests and Deacons and confirms members into the Diocese.