first water vs superiority

first water and superiority both are nouns.

Word	Noun	Adjective	Verb	Adverb
first water	Yes	No	No	No
superiority	Yes	No	No	No

As nouns, superiority is a hypernym of first water; that is, superiority is a word with a broader meaning than first water:

Other hypernyms of first water include high quality.

first water (noun)	superiority (noun)
the highest quality gems	the quality of being superior
	the quality of being at a competitive advantage
	displaying a sense of being better than others
	the state of excelling or surpassing or going beyond usual limits