Deacon vs Priest
The Roman Catholic, Eastern Catholic, Eastern and Oriental Orthodox, Anglican, Assyrian, Old and Independent Catholic, and Lutheran churches have three Holy Orders which refer to the ordination of certain individuals for a ministry.
These churches consider ordination as a sacrament and can be bestowed only by a bishop which is considered the teacher of the faith and the carrier of tradition from which the Holy Spirit flows through to the rest of the congregation.
The bishop is the highest of the Holy Orders, and he is considered as a modern day apostle. The Pope, cardinals, and archbishops are types of bishop who can celebrate all of the sacraments. A bishop leads a diocese which is composed of parishes headed by a priest.
The priest is the second highest of the Holy Orders. He assists the bishop and can perform the sacraments excluding the Holy Orders. The priest can celebrate Mass and the Eucharist, the Sacraments of Penance, Anointing the Sick, Baptism, and Matrimony.
Priests have been around since ancient times, and while today becoming a priest is a personal choice, before it was inherited and passed down in families. They perform all sacred rites of religion and serve as mediator between humans and God.
There are many requirements before one can become a priest. One is that he must be celibate, and although some Eastern and Orthodox churches accept married men to the priesthood, after ordination they cannot marry even if they are widowed.
A deacon, on the other hand, is the third of the Holy Orders. Deacons can serve as clerks or laymen in the church. It is a final step towards ordination to become a priest. Before the Second Vatican Council only seminarians were ordained as deacons.
Today, even those who are not studying to become priests can be ordained as deacons of the church. They assist the priest and are under their supervision, but they report directly to the bishop. Their duties include proclaiming the Gospel during Mass, ministering the Holy Communion, and being of service to the parishioners.
Unlike priests, they cannot perform the Holy Sacraments, but they assist the priest in their duties. In church services that do not involve the celebration of the Mass, deacons can preside.
Summary:
1.A priest is the second highest of the Holy Orders of the Roman Catholic, Eastern and Orthodox Christian churches while a deacon is the third of the Holy Orders.
2.A priest can celebrate the Mass and all Sacraments except the Holy Order while a deacon cannot perform any of the sacraments, but they can preside over services that do not involve the celebration of the Mass.
3.A priest must never marry while a married man can become a deacon but is expected to become celibate when he is widowed.
4.Before the Second Vatican Council, only candidates to the priesthood can become deacons, but today, even those who are not seminarians can be deacons.
5.Priests are assistants to the bishop and the Pope while deacons are servants of the church and the bishops.