plugboard vs telephone exchange

plugboard and telephone exchange both are nouns.

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

As nouns, telephone exchange is a hypernym of plugboard; that is, telephone exchange is a word with a broader meaning than plugboard:

plugboard: telephone central where circuits are completed with patchcords
telephone exchange: a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication

Other hypernyms of plugboard include central, exchange.

plugboard (noun)	telephone exchange (noun)
telephone central where circuits are completed with patchcords	a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication