twenty-one vs cardinal

twenty-one and cardinal both are nouns.

Word	Noun	Adjective	Verb	Adverb
twenty-one	Yes	Yes	No	No
cardinal	Yes	Yes	No	No

twenty-one (noun)	cardinal (noun)
a gambling game using cards; the object is to hold cards having a higher count than those dealt to the banker up to but not exceeding 21	crested thick-billed North American finch having bright red plumage in the male
the cardinal number that is the sum of twenty and one	a variable color averaging a vivid red
	(Roman Catholic Church) one of a group of more than 100 prominent bishops in the Sacred College who advise the Pope and elect new Popes
	the number of elements in a mathematical set; denotes a quantity but not the order

twenty-one (adjective)	cardinal (adjective)
being one more than twenty	being or denoting a numerical quantity but not order
	serving as an essential component