water fountain vs drinking fountain

water fountain and drinking fountain both are nouns.

Word	Noun	Adjective	Verb	Adverb
water fountain	Yes	No	No	No
drinking fountain	Yes	No	No	No

As nouns, water fountain and drinking fountain are synonyms defined as:

water fountain and drinking fountain: a public fountain to provide a jet of drinking water

Other synonyms of water fountain include bubbler.

water fountain (noun)	drinking fountain (noun)
a public fountain to provide a jet of drinking water	a public fountain to provide a jet of drinking water