major tranquilliser vs antipsychotic agent

major tranquilliser and antipsychotic agent both are nouns.

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

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

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

major tranquilliser (noun)	antipsychotic agent (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