junky vs cocaine addict

junky and cocaine addict both are nouns.

Word	Noun	Adjective	Verb	Adverb
junky	Yes	No	No	No
cocaine addict	Yes	No	No	No

As nouns, cocaine addict is a hyponym of junky; that is, cocaine addict is a word with a more specific, narrower meaning than junky:

Other hyponyms of junky include binger, crack addict, heroin addict, opium addict, opium taker, withdrawer.

junky (noun)	cocaine addict (noun)
a narcotics addict	a person addicted to cocaine
someone who is so ardently devoted to something that it resembles an addiction