thermal spring vs fountain

thermal spring and fountain both are nouns.

Word	Noun	Adjective	Verb	Adverb
thermal spring	Yes	No	No	No
fountain	Yes	No	No	No

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

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

thermal spring (noun)	fountain (noun)
a natural spring of water at a temperature of 70 F or above	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