gap vs crevice

gap and crevice both are nouns.

Word	Noun	Adjective	Verb	Adverb
gap	Yes	No	Yes	No
crevice	Yes	No	No	No

As nouns, crevice is a hyponym of gap; that is, crevice is a word with a more specific, narrower meaning than gap:

gap (noun)	crevice (noun)
an act of delaying or interrupting the continuity	a long narrow cleft
a narrow opening	a long narrow depression in a surface
a conspicuous disparity or difference as between two figures
a difference (especially an unfortunate difference) between two opinions or two views or two situations
an open or empty space in or between things
a pass between mountain peaks; geomorphological term for the lowest point on a mountain ridge between two peaks

gap (verb)	crevice (verb)
make an opening or gap in