The Bishop is the first and highest degree of the clergy in the Orthodox Church (episkopos in Greek, which means overseer). He is the successor to the Apostles in the service and government of the Church. A bishop is responsible for and the head of all the parishes located in his diocese. All authority of the lower orders of clergy is derived from the bishop. No divine services may be served in any Orthodox temple without the authorization of a bishop.
Rankings of Bishops
Sacramentally, all bishops are equal. Nevertheless, there are distinctions of administrative rank among bishops.
A bishop who governs his own diocese or archdiocese is a diocesan bishop. He may be called 'Bishop' or 'Archbishop' or 'Metropolitan' or 'Metropolitan Archbishop' or 'Patriarch'.
The title patriarch is reserved for the primate of certain of the autocephalous Orthodox churches. The first hierarch of the other autocephalous churches are styled metropolitan or archbishop or metropolitan archbishop.
The title patriarch was first applied to the original three major sees of Rome, Alexandria, and Antioch, and shortly after extended to include Constantinople and Jerusalem.
Much later the term was granted to the heads of other most significant Churches. Significance for some Churches now, may be more historical than actual.
Archbishops and Metropolitans
The title of archbishop or metropolitan may be granted to a senior bishop, usually one who is in charge of a large ecclesiastical jurisdiction. He may or may not have provincial oversight of suffragan bishops. He may or may not have auxilliary bishops assisting him.
In the Slavonic and Antiochian traditions, a metropolitan outranks an archbishop. The reverse is the situation in the Greek tradition. The Antiochian tradition also uses the style metropolitan archbishop to differentiate from metropolitan bishops in the Greek tradition.
The change in the Greek tradition came about in later Greek history, because the diocesan bishops of ancient sees (which in the Greek world are pretty much all of them) came to be styled metropolitans.
The Slavonic and Antiochian Churches continue to follow the older tradition, where an archbishop is a senior bishop in charge of a major see, and a metropolitan is a bishop in charge of a province which may include a number of minor and/or major sees.
In the Greek tradition, all diocesan bishops (with a few exceptions) are now metropolitans, and an archbishop holds his title as an indication of greater importance for whatever reason.
Non Ruling Bishops
A bishop who does not rule his own diocese is either a Patriarchal Vicar or an Auxilliary Bishop.
In the Church of Antioch, a bishop who is in charge of a newly-created diocese on behalf of, and under the supervision of, the Patriarch of Antioch is called a Patriarchal Vicar. The diocese is usually kept under the direct control of the patriarch until it becomes self-supporting. Patriarchal Vicars are not members of the Holy Synod, and do not answer to the Holy Synod.
When a diocese becomes self-supporting, it is usually granted a ruling bishop who becomes a member of the Holy Synod.
The equivalent title in some Orthodox jurisdictions is Exarch.
The equivalent title in the Roman Catholic Church is Vicar Apostolic.
Auxilliary Bishops are significantly different from Patriarchal Vicars.
Most Orthodox Churches allow themselves the capacity to appoint Auxilliary Bishops to assist ruling bishops within their own dioceses or archdioceses.
Auxilliary Bishops do not govern in their own right but only act as directed by their diocesan bishop.
The primate of the Church of Constantinople assumed the title Ecumenical Patriarch. The primate of the Church of Alexandria was granted the title Pope and Patriarch. The primate of the Church of Georgia recently amended his title from Catholicos to Catholicos-Patriarch.
In general, when referring to a hierarch, His is often used (e.g. His All Holiness, BARTHOLOMEW, Archbishop of Constantinople, New Rome and Ecumenical Patriarch visited Tarpon Springs, Florida in January of 2006). When speaking to a hierarch Your is often used (Your Eminence, I'm so glad to see you!).