mountain pass vs col

mountain pass and col both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain pass	Yes	No	No	No
col	Yes	No	No	No

As nouns, col is a hyponym of mountain pass; that is, col is a word with a more specific, narrower meaning than mountain pass:

mountain pass: the location in a range of mountains of a geological formation that is lower than the surrounding peaks
col: a pass between mountain peaks; geomorphological term for the lowest point on a mountain ridge between two peaks

Other hyponyms of mountain pass include gap, defile, gorge, saddle, saddleback.

mountain pass (noun)	col (noun)
the location in a range of mountains of a geological formation that is lower than the surrounding peaks	a pass between mountain peaks; geomorphological term for the lowest point on a mountain ridge between two peaks