Byzantine vs Byzantium

Byzantine and Byzantium both are nouns.

Word	Noun	Adjective	Verb	Adverb
Byzantine	Yes	Yes	No	No
Byzantium	Yes	No	No	No

Byzantine (noun)	Byzantium (noun)
a native or inhabitant of Byzantium or of the Byzantine Empire	an ancient city on the Bosporus founded by the Greeks; site of modern Istanbul; in 330 Constantine I rebuilt the city and called it Constantinople and made it his capital
	a continuation of the Roman Empire in the Middle East after its division in 395

Byzantine (adjective)	Byzantium (adjective)
of or relating to or characteristic of the Byzantine Empire or the ancient city of Byzantium
of or relating to the Eastern Orthodox Church or the rites performed in it
highly complex or intricate and occasionally devious