cardinal vs 0

cardinal and 0 both are nouns.

Word	Noun	Adjective	Verb	Adverb
cardinal	Yes	Yes	No	No
0	Yes	Yes	No	No

cardinal (noun)	0 (noun)
crested thick-billed North American finch having bright red plumage in the male	a mathematical element that when added to another number yields the same number
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

cardinal (adjective)	0 (adjective)
being or denoting a numerical quantity but not order	indicating the absence of any or all units under consideration
serving as an essential component