natural spring vs fountain

natural spring and fountain both are nouns.

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

As nouns, natural spring and fountain are synonyms defined as:

Other synonyms of natural spring include outflow, outpouring, spring.

natural spring (noun)	fountain (noun)
a natural flow of ground water	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