ordinal vs number 1

ordinal and number 1 both are nouns.

Word	Noun	Adjective	Verb	Adverb
ordinal	Yes	Yes	No	No
number 1	Yes	No	No	No

As nouns, number 1 is a hyponym of ordinal; that is, number 1 is a word with a more specific, narrower meaning than ordinal:

Other hyponyms of ordinal include first, number one.

ordinal (noun)	number 1 (noun)
the number designating place in an ordered sequence	the first element in a countable series

ordinal (adjective)	number 1 (adjective)
being or denoting a numerical order in a series
of or relating to a taxonomic order