telephone exchange vs telephone system

telephone exchange and telephone system both are nouns.

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

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