psychedelic drug vs hallucinogen

psychedelic drug and hallucinogen both are nouns.

Word	Noun	Adjective	Verb	Adverb
psychedelic drug	Yes	No	No	No
hallucinogen	Yes	No	No	No

As nouns, psychedelic drug and hallucinogen are synonyms defined as:

psychedelic drug and hallucinogen: a psychoactive drug that induces hallucinations or altered sensory experiences

Other synonyms of psychedelic drug include hallucinogenic drug, psychodelic drug.

psychedelic drug (noun)	hallucinogen (noun)
a psychoactive drug that induces hallucinations or altered sensory experiences	a psychoactive drug that induces hallucinations or altered sensory experiences