antipsychotic vs major tranquilizer

antipsychotic and major tranquilizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
antipsychotic	Yes	No	No	No
major tranquilizer	Yes	No	No	No

As nouns, antipsychotic and major tranquilizer are synonyms defined as:

antipsychotic and major tranquilizer: tranquilizer used to treat psychotic conditions when a calming effect is desired

antipsychotic (noun)	major tranquilizer (noun)
tranquilizer used to treat psychotic conditions when a calming effect is desired	tranquilizer used to treat psychotic conditions when a calming effect is desired