What are the differences between the eastern emperor of the western empire and the Byzantine emperor?

Answer 1

There was not such a thing as an eastern emperor of the western empire.

In 284 the Emperor Diocletian created a co-emperorship with one emperor in charge of the eastern part of the empire and one in charge of the western part and designated Nicomedia (in nothwestern Turkey) as the imperial capital of the east and Milan as the imperial capital of the west. Constantine the great moved the capital of the east to the nearby Byzantium, which he redeveloped and called Constantinople. After this there were alternations between period of sole emperorship (of the whole empire) and co-emperorship (again with one emperor in the east and one in the west). Finally in the late 4th century these two parts of the empire became separate as the western part started to crumble under the weight of Germanic peoples who took over all its lands except for Italy and fell. The eastern part of the Roman Empire was not affected by these invasions and continued to exist for another 1,000 years, until it fell in 1453.

Byzantine Empire is a term coined by historians to indicate the eastern part of the Roman Empire after the fall of the western part. The Romans did not use this term, they called it Roman Empire and Romania (this referred to this empire and not the country which was later called Romania).

The term Byzantine is derived from Byzantium, the Greek city which was redeveloped, turned into the imperial capital of the eastern part of the Roman Empire and renamed Constantinople by emperor Constantine the Great in 330. It is used to indicate the fact that not long after the fall of the west, this empire became centred on Greece and Greek in character after it lost most of its non-Greek territories. Greek replaced Latin as the official language of this empire in 620, some 150 years after the fall of the west.