heroin vs opiate

heroin and opiate both are nouns.

Word	Noun	Adjective	Verb	Adverb
heroin	Yes	No	No	No
opiate	Yes	No	No	No

As nouns, opiate is a hypernym of heroin; that is, opiate is a word with a broader meaning than heroin:

heroin: a narcotic that is considered a hard drug; a highly addictive morphine derivative; intravenous injection provides the fastest and most intense rush
opiate: a narcotic drug that contains opium or an opium derivative

Other hypernyms of heroin include hard drug.

heroin (noun)	opiate (noun)
a narcotic that is considered a hard drug; a highly addictive morphine derivative; intravenous injection provides the fastest and most intense rush	a narcotic drug that contains opium or an opium derivative