cog railway vs railway

cog railway and railway both are nouns.

Word	Noun	Adjective	Verb	Adverb
cog railway	Yes	No	No	No
railway	Yes	No	No	No

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

cog railway: railway for steep mountains; a cogwheel on the locomotive engages cogs on a center rail to provide traction
railway: line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight

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

cog railway (noun)	railway (noun)
railway for steep mountains; a cogwheel on the locomotive engages cogs on a center rail to provide traction	line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight
	a line of track providing a runway for wheels