fold up vs crumple

fold up and crumple both are verbs.

Word	Noun	Adjective	Verb	Adverb
fold up	No	No	Yes	No
crumple	No	No	Yes	No

As verbs, crumple is a hyponym of fold up; that is, crumple is a word with a more specific, narrower meaning than fold up:

Other hyponyms of fold up include crease, crinkle, rumple, wrinkle.

fold up (verb)	crumple (verb)
become folded or folded up	become wrinkled or crumpled or creased
bend or lay so that one part covers the other	to gather something into small wrinkles or folds
	fold or collapse
	fall apart