number one vs ordinal

number one and ordinal both are nouns.

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

As nouns, ordinal is a hypernym of number one; that is, ordinal is a word with a broader meaning than number one:

Other hypernyms of number one include no., ordinal number.

number one (noun)	ordinal (noun)
a reference to yourself or myself etc.; `take care of number one' means to put your own interests first	the number designating place in an ordered sequence
the first element in a countable series
the first or highest in an ordering or series

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