quadriphonic system vs quadraphony

quadriphonic system and quadraphony both are nouns.

Word	Noun	Adjective	Verb	Adverb
quadriphonic system	Yes	No	No	No
quadraphony	Yes	No	No	No

As nouns, quadriphonic system and quadraphony are synonyms defined as:

quadriphonic system and quadraphony: a stereophonic sound recording or reproducing system using four separate channels

Other synonyms of quadriphonic system include quadraphonic system.

quadriphonic system (noun)	quadraphony (noun)
a stereophonic sound recording or reproducing system using four separate channels	a stereophonic sound recording or reproducing system using four separate channels