stimulate vs impact

stimulate is not a noun while impact is a noun.

Word	Noun	Adjective	Verb	Adverb
stimulate	No	No	Yes	No
impact	Yes	No	Yes	No

As verbs, impact is a hypernym of stimulate; that is, impact is a word with a broader meaning than stimulate:

Other hypernyms of stimulate include affect, bear on, bear upon, touch, touch on.

stimulate (noun)	impact (noun)
	influencing strongly
	the violent interaction of individuals or groups entering into combat
	the striking of one body against another
	a forceful consequence; a strong effect

stimulate (verb)	impact (verb)
cause to be alert and energetic	have an effect upon
act as a stimulant	press or wedge together; pack together
provide the needed stimulus for
cause to do; cause to act in a specified manner
cause to occur rapidly
stir the feelings, emotions, or peace of
stir feelings in