In that case the chief bishop is called the diocesan. Assisting bishops are usually called suffragan bishops. An assisting bishop who will succeed the diocesan is a bishop coadjutor. Usually a priest is the chief minister in a local congregation. A deacon, like a bishop or priest, is an ordained minister.
Deacon comes from the Greek word, diakonos, meaning servant.
Deacons usually serve in local congregations and have a special ministry to the poor, the sick and the troubled. Deacons are addressed as deacon, mister, miss, mrs., etc. In the Episcopal Church lay persons as well as bishops, priests and deacons are ministers, servants of God, caring for their brothers and sisters in the church and those outside it. Preaching is only one function of the ordained ministry in the Episcopal Church and so preacher is not an appropriate synonym for bishop, priest or deacon. The priest in charge of a parish, a self-supporting church, is the rector.