roll up vs pile up

roll up and pile up both are verbs.

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

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

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

roll up (verb)	pile up (verb)
form a cylinder by rolling	increase in amount by collecting or gathering
form into a cylinder by rolling	arrange into piles or stacks
show certain properties when being rolled	get or gather together
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