mental institution vs hospital

mental institution and hospital both are nouns.

Word	Noun	Adjective	Verb	Adverb
mental institution	Yes	No	No	No
hospital	Yes	No	No	No

As nouns, hospital is a hypernym of mental institution; that is, hospital is a word with a broader meaning than mental institution:

mental institution: a hospital for mentally incompetent or unbalanced person
hospital: a health facility where patients receive treatment

Other hypernyms of mental institution include infirmary.

mental institution (noun)	hospital (noun)
a hospital for mentally incompetent or unbalanced person	a health facility where patients receive treatment
	a medical institution where sick or injured people are given medical or surgical care