scrunch vs fold up

scrunch is a noun but fold up is not a noun.

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

As verbs, fold up is a hypernym of scrunch; that is, fold up is a word with a broader meaning than scrunch:

scrunch: make wrinkles or creases on a smooth surface; make a pressed, folded or wrinkled line in; `crisp' is archaic
fold up: bend or lay so that one part covers the other

Other hypernyms of scrunch include fold, turn up.

scrunch (noun)	fold up (noun)
a crunching noise

scrunch (verb)	fold up (verb)
make wrinkles or creases on a smooth surface; make a pressed, folded or wrinkled line in; `crisp' is archaic	become folded or folded up
sit on one's heels	bend or lay so that one part covers the other
make a noise typical of an engine lacking lubricants