insane asylum vs mental hospital

insane asylum and mental hospital both are nouns.

Word	Noun	Adjective	Verb	Adverb
insane asylum	Yes	No	No	No
mental hospital	Yes	No	No	No

As nouns, insane asylum and mental hospital are synonyms defined as:

insane asylum and mental hospital: a hospital for mentally incompetent or unbalanced person

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

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