cable railway vs railroad line

cable railway and railroad line both are nouns.

Word	Noun	Adjective	Verb	Adverb
cable railway	Yes	No	No	No
railroad line	Yes	No	No	No

As nouns, railroad line is a hypernym of cable railway; that is, railroad line is a word with a broader meaning than cable railway:

cable railway: a railway up the side of a mountain pulled by a moving cable and having counterbalancing ascending and descending cars
railroad line: line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight

Other hypernyms of cable railway include railroad, railway, railway line, railway system.

cable railway (noun)	railroad line (noun)
a railway up the side of a mountain pulled by a moving cable and having counterbalancing ascending and descending cars	line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight