telephone system vs telephone set

telephone system and telephone set both are nouns.

Word	Noun	Adjective	Verb	Adverb
telephone system	Yes	No	No	No
telephone set	Yes	No	No	No

telephone system (noun)	telephone set (noun)
a communication system that transmits sound between distant points	electronic equipment that converts sound into electrical signals that can be transmitted over distances and then converts received signals back into sounds