agentes vices
Officials of the Roman and of the Early Byzantine Empire. They had administrative responsibilities being in the service of the praetorian prefects.

comes
1. A title in the Roman and the Byzantine Empires, designating an official with political but mostly military jurisdiction. Especially the comes Orientis held the position corresponding to that of a vicar in Early Byzantine period. In the years of Justinian I, the comes in head of wider provinces assumed political and military powers, while in the Middle Byzantine period the Opsikion theme was one of the few themes which was the jurisdiction of a comes instead of a strategos.2. A nobility title in medieval Europe.

praefectus Augustalis
A functionary responsible for the diocese of Egypt in Late Antiquity/Early Byzantine years. He was actually a vicar with somewhat wider responsibilities.

praetorian prefect (praefectus praetorio)
Commander of the emperor's bodyguard under the principate. During the regne of Constantine I the praetorian prefect becomes a dignitary responsible for the administrative unit called the prefecture, which was subdivided into dioceses. In 400 A.D. there were four such praetorian prefectures, of Oriens, of Illyricum, of Illyricum, Italia and Africa and of Gallia. The praetorian prefects were second only to the emperor. The praetorian prefect of Oriens was the mightiest among prefects. His office is for the last time mentioned in 680.

praetorian prefecture (praefecura praitorio)
In Late Roman Empire it was the basic administrative unit. Prefectures were estabished by Constantine I (4th century). The Empire was then divided to four praetorian prefectures: i) praefectura praetorio per Orientem (prefecture of Oriens), ii) praefectura praetorio Galliarum (prefecture of Galliae), iii) praefectura praetorio per Illyricum (prefecture of Illyricum), iv) praefectura praetorio Italiae, Illyrici et Africae (prefecture of Italia and Africa).

vicarius
Τhe term refers to the substitute of various officials. Since the 3rd century, the vicarius replaced mostly procuratores from the equestrian class. The most important vicarii were those who replaced the Praetorian eparchs in the dioceses set up by Diocletian. In addition, the vicarii could have military (like the command of the garrison in Egypt) or even judicial responsibilities.