fold up vs crimp

fold up is not a noun while crimp is a noun.

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

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

fold up (noun)	crimp (noun)
	a lock of hair that has been artificially waved or curled
	someone who tricks or coerces men into service as sailors or soldiers
	an angular or rounded shape made by folding

fold up (verb)	crimp (verb)
become folded or folded up	curl tightly
bend or lay so that one part covers the other	make ridges into by pinching together