stimulation vs natural process

stimulation and natural process both are nouns.

Word	Noun	Adjective	Verb	Adverb
stimulation	Yes	No	No	No
natural process	Yes	No	No	No

As nouns, natural process is a hypernym of stimulation; that is, natural process is a word with a broader meaning than stimulation:

stimulation: (physiology) the effect of a stimulus (on nerves or organs etc.)
natural process: a process existing in or produced by nature (rather than by the intent of human beings)

Other hypernyms of stimulation include action, activity, natural action.

stimulation (noun)	natural process (noun)
the act of arousing an organism to action	a process existing in or produced by nature (rather than by the intent of human beings)
mutual sexual fondling prior to sexual intercourse
any stimulating information or event; acts to arouse action
(physiology) the effect of a stimulus (on nerves or organs etc.)