Bishop of Rome vs Pope Urban VI

Bishop of Rome and Pope Urban VI both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bishop of Rome	Yes	No	No	No
Pope Urban VI	Yes	No	No	No

Bishop of Rome (noun)	Pope Urban VI (noun)
the head of the Roman Catholic Church	Italian pope from 1378 to 1389 whose contested election began the Great Schism; he alienated his political allies by his ruthless treatment of his opponents (1318-1389)