heroin vs big H

heroin and big H both are nouns.

Word	Noun	Adjective	Verb	Adverb
heroin	Yes	No	No	No
big H	Yes	No	No	No

As nouns, big H is a hyponym of heroin; that is, big H is a word with a more specific, narrower 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
big H: street names for heroin

Other hyponyms of heroin include hell dust, nose drops, scag, skag, smack, thunder.

heroin (noun)	big H (noun)
a narcotic that is considered a hard drug; a highly addictive morphine derivative; intravenous injection provides the fastest and most intense rush	street names for heroin