natural spring vs outpouring

natural spring and outpouring both are nouns.

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

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

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

natural spring (noun)	outpouring (noun)
a natural flow of ground water	a large flow
	the rapid and continuous delivery of linguistic communication (spoken or written)
	the pouring forth of a fluid
	a sudden rapid flow (as of water)
	a natural flow of ground water