roll up vs chunk

roll up is not a noun while chunk is a noun.

Word	Noun	Adjective	Verb	Adverb
roll up	No	No	Yes	No
chunk	Yes	No	Yes	No

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

Other hyponyms of roll up include run up, corral, collect, pull in, come up, scrape, scrape up, scratch, lump, bale, catch, fund, fund.

roll up (noun)	chunk (noun)
	a compact mass
	a substantial amount

roll up (verb)	chunk (verb)
form a cylinder by rolling	group or chunk together in a certain order or place side by side
form into a cylinder by rolling	put together indiscriminately
show certain properties when being rolled
make into a bundle
close (a car window) by causing it to move up, as with a handle
arrive in a vehicle:
get or gather together