Holy Orders

Holy Orders is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time: thus it is the sacrament of apostolic ministry. It includes three degrees: episcopate, presbyterate, and diaconate. (1536)

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Today the word "ordination" is reserved for the sacramental act which integrates a man into the order of bishops, presbyters, or deacons, and goes beyond a simple election, designation, delegation, or institution by the community, for it confers a gift of the Holy Spirit that permits the exercise of a "sacred power" (sacra potestas) which can come only from Christ himself through his Church.
Ordination

Ordination is also called consecration, it is a setting apart and an investiture by Christ himself for his Church. the laying on of hands by the Bishop, with the consecratory prayer, constitutes the visible sign of this ordination.