Bishop of Rome vs Calixtus II

Bishop of Rome and Calixtus II both are nouns.

Word	Noun	Adjective	Verb	Adverb
Bishop of Rome	Yes	No	No	No
Calixtus II	Yes	No	No	No

Bishop of Rome (noun)	Calixtus II (noun)
the head of the Roman Catholic Church	pope who in 1122 forced the Holy Roman Emperor Henry V to sign a concordat that recognized the right of the church to choose its own leadership (died in 1124)