twenty-eight vs 28

twenty-eight and 28 both are nouns.

Word	Noun	Adjective	Verb	Adverb
twenty-eight	Yes	Yes	No	No
28	Yes	Yes	No	No

As adjectives, twenty-eight and 28 are synonyms defined as:

Other synonyms of twenty-eight include xxviii.

As nouns, twenty-eight and 28 are synonyms defined as:

twenty-eight and 28: the cardinal number that is the sum of twenty-seven and one

Other synonyms of twenty-eight include XXVIII.

twenty-eight (noun)	28 (noun)
the cardinal number that is the sum of twenty-seven and one	the cardinal number that is the sum of twenty-seven and one

twenty-eight (adjective)	28 (adjective)
being eight more than twenty	being eight more than twenty