psychoactive substance vs psychoactive drug

psychoactive substance and psychoactive drug both are nouns.

Word	Noun	Adjective	Verb	Adverb
psychoactive substance	Yes	No	No	No
psychoactive drug	Yes	No	No	No

As nouns, psychoactive substance and psychoactive drug are synonyms defined as:

psychoactive substance and psychoactive drug: a drug that can produce mood changes and distorted perceptions

Other synonyms of psychoactive substance include consciousness-altering drug, mind-altering drug.

psychoactive substance (noun)	psychoactive drug (noun)
a drug that can produce mood changes and distorted perceptions	a drug that can produce mood changes and distorted perceptions