ordinal vs twenty-eighth

ordinal is a noun but twenty-eighth is not a noun.

Word	Noun	Adjective	Verb	Adverb
ordinal	Yes	Yes	No	No
twenty-eighth	No	Yes	No	No

ordinal (noun)	twenty-eighth (noun)
the number designating place in an ordered sequence

ordinal (adjective)	twenty-eighth (adjective)
being or denoting a numerical order in a series	coming next after the twenty-seventh in position
of or relating to a taxonomic order