rack up vs ace

rack up is not a noun while ace is a noun.

Word	Noun	Adjective	Verb	Adverb
rack up	No	No	Yes	No
ace	Yes	Yes	Yes	No

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

Other hyponyms of rack up include par, shoot, convert, homer, kick, eagle, hole up, walk, equalise, equalize, get even, get, have, make.

rack up (noun)	ace (noun)
	a serve that the receiver is unable to reach
	one of four playing cards in a deck having a single pip on its face
	someone who is dazzlingly skilled in any field
	the smallest whole number or a numeral representing this number

rack up (adjective)	ace (adjective)
	of the highest quality

rack up (verb)	ace (verb)
supply a rack with feed for (horses or other animals)	score an ace against
defeat thoroughly	serve an ace against (someone)
gain points in a game	play (a hole) in one stroke
place in a rack	succeed at easily