mental hospital vs mental institution

mental hospital and mental institution both are nouns.

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

As nouns, mental hospital and mental institution are synonyms defined as:

mental hospital and mental institution: a hospital for mentally incompetent or unbalanced person

Other synonyms of mental hospital include asylum, insane asylum, institution, mental home, psychiatric hospital.

mental hospital (noun)	mental institution (noun)
a hospital for mentally incompetent or unbalanced person	a hospital for mentally incompetent or unbalanced person