grade separation vs crosswalk

grade separation and crosswalk both are nouns.

Word	Noun	Adjective	Verb	Adverb
grade separation	Yes	No	No	No
crosswalk	Yes	No	No	No

As nouns, crosswalk is a hypernym of grade separation; that is, crosswalk is a word with a broader meaning than grade separation:

grade separation: a crossing that uses an underpass or overpass
crosswalk: a path (often marked) where something (as a street or railroad) can be crossed to get from one side to the other

Other hypernyms of grade separation include crossing, crossover.

grade separation (noun)	crosswalk (noun)
a crossing that uses an underpass or overpass	a path (often marked) where something (as a street or railroad) can be crossed to get from one side to the other