freshwater vs rain

freshwater and rain both are nouns.

Word	Noun	Adjective	Verb	Adverb
freshwater	Yes	No	No	No
rain	Yes	No	Yes	No

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

Other hyponyms of freshwater include rainwater, condensate.

freshwater (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

freshwater (verb)	rain (verb)
	precipitate as rain