crag vs drop-off

crag and drop-off both are nouns.

Word	Noun	Adjective	Verb	Adverb
crag	Yes	No	No	No
drop-off	Yes	No	No	No

As nouns, drop-off is a hypernym of crag; that is, drop-off is a word with a broader meaning than crag:

Other hypernyms of crag include cliff, drop.

crag (noun)	drop-off (noun)
a steep rugged rock or cliff	a change downward
	a steep high face of rock
	a noticeable deterioration in performance or quality