geyser vs fountain

geyser and fountain both are nouns.

Word	Noun	Adjective	Verb	Adverb
geyser	Yes	No	Yes	No
fountain	Yes	No	No	No

As nouns, fountain is a hypernym of geyser; that is, fountain is a word with a broader meaning than geyser:

Other hypernyms of geyser include natural spring, outflow, outpouring, spring.

geyser (noun)	fountain (noun)
a spring that discharges hot water and steam	a plumbing fixture that provides a flow of water
	an artificially produced flow of water
	a structure from which an artificially produced jet of water arises
	a natural flow of ground water

geyser (verb)	fountain (verb)
to overflow like a geyser