pile up vs bale

pile up is not a noun while bale is a noun.

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

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

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

pile up (noun)	bale (noun)
	a large bundle bound for storage or transport

pile up (verb)	bale (verb)
increase in amount by collecting or gathering	make into a bale
arrange into piles or stacks
get or gather together