Roman Church vs Western Church

Roman Church and Western Church both are nouns.

Word	Noun	Adjective	Verb	Adverb
Roman Church	Yes	No	No	No
Western Church	Yes	No	No	No

As nouns, Roman Church and Western Church are synonyms defined as:

Roman Church and Western Church: the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy

Other synonyms of Roman Church include Church of Rome, Roman Catholic, Roman Catholic Church.

Roman Church (noun)	Western Church (noun)
the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy	the Christian Church based in the Vatican and presided over by a pope and an episcopal hierarchy