drug addict vs junky

drug addict and junky both are nouns.

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

As nouns, drug addict and junky are synonyms defined as:

Other synonyms of drug addict include junkie.

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