prowess vs superior skill

prowess and superior skill both are nouns.

Word	Noun	Adjective	Verb	Adverb
prowess	Yes	No	No	No
superior skill	Yes	No	No	No

As nouns, superior skill is a hypernym of prowess; that is, superior skill is a word with a broader meaning than prowess:

prowess: a superior skill that you can learn by study and practice and observation
superior skill: more than ordinary ability

prowess (noun)	superior skill (noun)
a superior skill that you can learn by study and practice and observation	more than ordinary ability