telephone system vs telephone exchange

telephone system and telephone exchange both are nouns.

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

telephone system (noun)	telephone exchange (noun)
a communication system that transmits sound between distant points	a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication