ruck up vs scrunch

ruck up is not a noun while scrunch is a noun.

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

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

ruck up: become wrinkled or drawn together
scrunch: make wrinkles or creases on a smooth surface; make a pressed, folded or wrinkled line in; `crisp' is archaic

Other hypernyms of ruck up include crease, crinkle, crisp, ruckle, scrunch up, wrinkle.

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

ruck up (verb)	scrunch (verb)
become wrinkled or drawn together	make wrinkles or creases on a smooth surface; make a pressed, folded or wrinkled line in; `crisp' is archaic
	sit on one's heels
	make a noise typical of an engine lacking lubricants