crumble vs ruin

crumble is not a noun while ruin is a noun.

Word	Noun	Adjective	Verb	Adverb
crumble	No	No	Yes	No
ruin	Yes	No	Yes	No

As verbs, ruin is a hyponym of crumble; that is, ruin is a word with a more specific, narrower meaning than crumble:

crumble (noun)	ruin (noun)
	destruction achieved by causing something to be wrecked or ruined
	a ruined building
	an event that results in destruction
	failure that results in a loss of position or reputation
	the process of becoming dilapidated
	an irrecoverable state of devastation and destruction

crumble (verb)	ruin (verb)
break or fall apart into fragments	fall into ruin
fall into decay or ruin	destroy completely; damage irreparably
fall apart	reduce to ruins
	deprive of virginity
	reduce to bankruptcy
	destroy or cause to fail