From The Visible Church, Lessons 3 and 4 deal with Bishops:
Diocese: from the Greek dioikesis, signifying management, government or a governed territory. When a diocese is ruled by an archbishop, it is known as an archdiocese.
Bishop: derived from the Greek episkopos, an overseer.
Archbishops have several grades:
1. Greater patriarchs, the archbishops of Jerusalem, Constantinople, Antioch, and Alexandria.
2. Patriarchs, a title given to certain archbishops, such as Venice and Lisbon.
3. Primates, now an honorary title only.
4. Metropolitans, who rule archdioceses and have certain rights and jurisdiction over the dioceses of their provinces [e.g., such as the way that the Archbishop of Chicago is the Metropolitan of the other surrounding dioceses in the area.]
5. Titular archbishops, who hold title but have no jurisdiction.
An archbishop is spoken of as Most Reverend and is addressed as Your Grace.
Different types of bishops:
1. Diocesan bishops, each of whom governs their own diocese.
2. Suffragan bishops are bishops of dioceses that form part of a province [see Metropolitans above].
3. Titular bishops, who like titular archbishops, bear the title of a diocese but have no jurisdiction over it.
4. Auxiliary bishops, who assist the bishop of a diocese.
5. Coadjutor bishops, who presently assist the bishop of the diocese, but by title are appointed by the Holy Father to succeed the incumbent bishop of his diocese.
A bishop is spoken of as Right Reverend, addressed as Your Excellency or My Lord, or in these more casual times, simply as Bishop.
Special Vestments of Bishops and Archbishops:
2. The mitre, a tall double-pointed cap, used in very early times as a head-dress for kings [you sometimes see the Magi depicted wearing something like a mitre]. Its two points symbolize the Old and New Testaments.
4. A bishop wears a purple biretta or cap, and may also wear a small skull cap, or zucchetto.
5. A bishop has a pastoral staff, or crosier, resembling a shepherd’s crook, and symbolizing his office as shepherd of the flock.
6. A bishop wears a pectoral cross (Latin pectus, the breast).
The visit Ad Limina: from the Latin “to the threshold”, every bishop is obliged at certain intervals (usually every five years) to visit Rome and make a report to the Pope.