PCP vs hallucinogen

PCP and hallucinogen both are nouns.

Word	Noun	Adjective	Verb	Adverb
PCP	Yes	No	No	No
hallucinogen	Yes	No	No	No

As nouns, hallucinogen is a hypernym of PCP; that is, hallucinogen is a word with a broader meaning than PCP:

PCP: a drug used as an anesthetic by veterinarians; illicitly taken (originally in the form of powder or `dust') for its effects as a hallucinogen
hallucinogen: a psychoactive drug that induces hallucinations or altered sensory experiences

Other hypernyms of PCP include hallucinogenic drug, psychedelic drug, psychodelic drug.

PCP (noun)	hallucinogen (noun)
a drug used as an anesthetic by veterinarians; illicitly taken (originally in the form of powder or `dust') for its effects as a hallucinogen	a psychoactive drug that induces hallucinations or altered sensory experiences
a person who helps in identifying or preventing or treating illness or disability