telephone line vs telegraph line

telephone line and telegraph line both are nouns.

Word	Noun	Adjective	Verb	Adverb
telephone line	Yes	No	No	No
telegraph line	Yes	No	No	No

As nouns, telephone line and telegraph line are synonyms defined as:

telephone line and telegraph line: the wire that carries telegraph and telephone signals

Other synonyms of telephone line include telegraph wire, telephone wire.

telephone line (noun)	telegraph line (noun)
a telephone connection	the wire that carries telegraph and telephone signals
the wire that carries telegraph and telephone signals