church mode vs Gregorian mode

church mode and Gregorian mode both are nouns.

Word	Noun	Adjective	Verb	Adverb
church mode	Yes	No	No	No
Gregorian mode	Yes	No	No	No

As nouns, church mode and Gregorian mode are synonyms defined as:

church mode and Gregorian mode: any of a system of modes used in Gregorian chants up until 1600; derived historically from the Greek mode

Other synonyms of church mode include ecclesiastical mode, medieval mode.

church mode (noun)	Gregorian mode (noun)
any of a system of modes used in Gregorian chants up until 1600; derived historically from the Greek mode	any of a system of modes used in Gregorian chants up until 1600; derived historically from the Greek mode