roll up vs amass

roll up and amass both are verbs.

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

As verbs, roll up and amass are synonyms defined as:

Other synonyms of roll up include accumulate, collect, compile, hoard, pile up.

roll up (verb)	amass (verb)
form a cylinder by rolling	increase in amount by collecting or gathering
form into a cylinder by rolling	get or gather together
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