Bishop of Rome vs Pope John Paul I

Bishop of Rome and Pope John Paul I both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bishop of Rome	Yes	No	No	No
Pope John Paul I	Yes	No	No	No

Bishop of Rome (noun)	Pope John Paul I (noun)
the head of the Roman Catholic Church	the first Pope to assume a double name; he reigned for only 34 days (1912-1978)