fresh water vs rain

fresh water and rain both are nouns.

Word	Noun	Adjective	Verb	Adverb
fresh water	Yes	No	No	No
rain	Yes	No	Yes	No

As nouns, rain is a hyponym of fresh water; that is, rain is a word with a more specific, narrower meaning than fresh water:

Other hyponyms of fresh water include rainwater, condensate.

fresh water (noun)	rain (noun)
water that is not salty	anything happening rapidly or in quick successive
	water falling in drops from vapor condensed in the atmosphere
	drops of fresh water that fall as precipitation from clouds

fresh water (verb)	rain (verb)
	precipitate as rain