rack railway vs cog railway

rack railway and cog railway both are nouns.

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

As nouns, rack railway and cog railway are synonyms defined as:

rack railway and cog railway: railway for steep mountains; a cogwheel on the locomotive engages cogs on a center rail to provide traction

rack railway (noun)	cog railway (noun)
railway for steep mountains; a cogwheel on the locomotive engages cogs on a center rail to provide traction	railway for steep mountains; a cogwheel on the locomotive engages cogs on a center rail to provide traction