neuroleptic agent vs major tranquilliser

neuroleptic agent and major tranquilliser both are nouns.

Word	Noun	Adjective	Verb	Adverb
neuroleptic agent	Yes	No	No	No
major tranquilliser	Yes	No	No	No

As nouns, neuroleptic agent and major tranquilliser are synonyms defined as:

neuroleptic agent and major tranquilliser: tranquilizer used to treat psychotic conditions when a calming effect is desired

neuroleptic agent (noun)	major tranquilliser (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