pain vs negative stimulus

pain and negative stimulus both are nouns.

Word	Noun	Adjective	Verb	Adverb
pain	Yes	No	Yes	No
negative stimulus	Yes	No	No	No

As nouns, negative stimulus is a hypernym of pain; that is, negative stimulus is a word with a broader meaning than pain:

pain (noun)	negative stimulus (noun)
a somatic sensation of acute discomfort	a stimulus with undesirable consequences
something or someone that causes trouble; a source of unhappiness
emotional distress; a fundamental feeling that people try to avoid
a symptom of some physical hurt or disorder

pain (verb)	negative stimulus (verb)
cause bodily suffering to and make sick or indisposed
cause emotional anguish or make miserable