The ecclesiastical title of archpriest or archpresbyter belongs to certain priests with supervisory duties over a number of parishes. The term is most often used in Eastern Orthodoxy and the Eastern Catholic Churches and may be somewhat analogous to a monsignor, vicar forane or dean in the Latin Church, but in the Eastern churches an archpriest wears an additional vestment and, typically, a pectoral cross, and becomes an archpriest via a liturgical ceremony. The term may be used in the Latin Catholic Church in certain historical titles and may replace in popular usage the title of vicar forane, otherwise often known as a dean. Antiquity
In ancient times, the archdeacon was the head of the deacons of a diocese, as is still the case in the Eastern Orthodox Church, while the archpriest was the chief of the presbyerate of the diocese, i.e. of the priests as a body. The latters  duties included deputising for the bishop in spiritual matters when necessary. Western Christianity
Latin Catholic Church
In the western Church, by the Middle Ages, the use of the title had evolved and became assigned to the priest of the principal parish among several local parishes. This priest had general charge of worship in this archpresbyterate, and the parishioners of the smaller parishes had to attend Sunday Mass and hold baptisms at the principal parish while the subordinate parishes instead held daily mass and homilies.
Eastern Christianity
Archpriest, also protopope (Greek: πρωτοπαπᾶς, protopapas) or protopresbyter (Greek: πρωτοπρεσβύτερος, protopresbyteros), is a clerical rank, a title of honor given to non-monastic priests and is conferred by a bishop with the laying on of hands and prayer. An archpriest typically wears an epigonation, a vestment originally worn only by bishops; however, details vary locally, and in some places being given the epigonation is an honor that typically precedes being made an archpriest and in other places, it is an honor that is given to only some archpriests. An archpriest also wears a pectoral cross both as part of his street clothes and when vested. The ceremony for making an archpriest is analogous to other clerical promotions bestowed with cheirothesia: at the little entrance of the divine liturgy, the candidate is conducted to the ambo in the middle of the church where the bishop is at the time, and the bishop blesses him and says a prayer addressed to Christ asking to "... endue our brother (name) with Thy Grace, and adorn him with virtue to stand at the head of the Presbyters of Thy people, and make him to be a good example to them that are with him ..."In the Russian tradition, protopresbyter is a higher rank than archpriest, as explained in a translation by the Orthodox Church in America:

Although entitled "for the making of a Protopresbyter" it is clear that what is now known as an "Archpriest" is what is usually meant.