The Sacrament of Holy Orders is a Sacrament that creates a Ministry in the Church, such as Bishop, Priest or Deacon. A Bishop is the pastor of the Diocese and leads the teaching of the Gospel as well as administering Sacraments such as Confirmation and Holy Orders. Priests will usually be assigned to a parish and will carry out many tasks within it as part of their Ministry alongside regularly saying Mass. A Deacon can also be assigned to a parish and will assist the Priest in the day to day pastoral work.
Taken from The Faith Of The Catholic Church a CTS Publication
209. How is the Sacrament of Orders conferred?
The Sacrament of Orders is conferred by the Bishop through the imposition of hands followed by a solemn consecratory prayer that calls on God to grant to the candidate the grace of the Holy Spirit required for his ministry that cannot be removed.
203. What are the different degrees in which the ordained ministry is exercised?
Traditionally, the ordained ministry is exercised in three degrees: Bishop, Priest and Deacon.