pile up vs scrape

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

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

As verbs, scrape is a hyponym of pile up; that is, scrape 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 up, scratch, chunk, lump, bale, catch, fund, fund.

pile up (noun)	scrape (noun)
	an indication of damage
	a deep bow with the foot drawn backwards (indicating excessive humility)
	a harsh noise made by scraping
	an abraded area where the skin is torn or worn off

pile up (verb)	scrape (verb)
increase in amount by collecting or gathering	scratch repeatedly
arrange into piles or stacks	bruise, cut, or injure the skin or the surface of
get or gather together	cut the surface of; wear away the surface of
	gather (money or other resources) together over time
	make by scraping
	bend the knees and bow in a servile manner