telephone circuit vs connection

telephone circuit and connection both are nouns.

Word	Noun	Adjective	Verb	Adverb
telephone circuit	Yes	No	No	No
connection	Yes	No	No	No

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

Other hypernyms of telephone circuit include connecter, connective, connector, connexion.

telephone circuit (noun)	connection (noun)
a telephone connection	the act of bringing two things into contact (especially for communication)
	shifting from one form of transportation to another
	an instrumentality that connects
	the process of bringing ideas or events together in memory or imagination
	a supplier (especially of narcotics)
	(usually plural) a person who is influential and to whom you are connected in some way (as by family or friendship)
	a relation between things or events (as in the case of one causing the other or sharing features with it)
	a connecting shape
	the state of being connected