thirty-eight vs 38

thirty-eight and 38 both are adjectives.

Word	Noun	Adjective	Verb	Adverb
thirty-eight	No	Yes	No	No
38	No	Yes	No	No

As adjectives, thirty-eight and 38 are synonyms defined as:

Other synonyms of thirty-eight include xxxviii.

thirty-eight (adjective)	38 (adjective)
being eight more than thirty	being eight more than thirty