Doctor of the Church vs Church of Rome

Doctor of the Church and Church of Rome both are nouns.

Word	Noun	Adjective	Verb	Adverb
Doctor of the Church	Yes	No	No	No
Church of Rome	Yes	No	No	No

Doctor of the Church (noun)	Church of Rome (noun)
(Roman Catholic Church) a title conferred on 33 saints who distinguished themselves through the orthodoxy of their theological teaching	the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy