twenty-five vs xxv

twenty-five is a noun but xxv is not a noun.

Word	Noun	Adjective	Verb	Adverb
twenty-five	Yes	Yes	No	No
xxv	No	Yes	No	No

As adjectives, twenty-five and xxv are synonyms defined as:

Other synonyms of twenty-five include 25.

twenty-five (noun)	xxv (noun)
the cardinal number that is the sum of twenty-four and one

twenty-five (adjective)	xxv (adjective)
being five more than twenty	being five more than twenty