The Catechism in Questions & Answers

413. What is the source of the spiritual ministry?

The spiritual ministry is founded upon the sending of Jesus Christ by God, the Father. Jesus Christ is thus the One sent by God. As such He is authorised, blessed, and sanctified for the redemption of mankind. The Apostles are those who have been sent by Jesus Christ.
The spiritual ministry is always linked to Jesus Christ and the Apostles sent by Him. Ministry and the apostolate therefore belong together: wherever the Apostle ministry is active, the spiritual ministry will also be present.

The term ‘apostolate’ is used primarily in reference to all bearers of the Apostle ministry as a whole (‘apostolate’ = the Apostles of Jesus). The priestly ministries and Deacons work by commission of the ‘apostolate’ and perform duties in pastoral care, preaching, and the dispensation of the sacraments.