MAOI vs antidepressant

MAOI and antidepressant both are nouns.

Word	Noun	Adjective	Verb	Adverb
MAOI	Yes	No	No	No
antidepressant	Yes	No	No	No

As nouns, antidepressant is a hypernym of MAOI; that is, antidepressant is a word with a broader meaning than MAOI:

MAOI: any of a group of antidepressant drugs that inhibit the action of monoamine oxidase in the brain and so allow monoamines to accumulate
antidepressant: any of a class of drugs used to treat depression; often have undesirable side effects

Other hypernyms of MAOI include antidepressant drug.

MAOI (noun)	antidepressant (noun)
any of a group of antidepressant drugs that inhibit the action of monoamine oxidase in the brain and so allow monoamines to accumulate	any of a class of drugs used to treat depression; often have undesirable side effects