addict vs user

addict and user both are nouns.

Word	Noun	Adjective	Verb	Adverb
addict	Yes	No	Yes	No
user	Yes	No	No	No

As nouns, user is a hypernym of addict; that is, user is a word with a broader meaning than addict:

Other hypernyms of addict include drug user, substance abuser.

addict (noun)	user (noun)
someone who is physiologically dependent on a substance or activity	a person who makes use of a thing; someone who uses or employs something
someone who is so ardently devoted to something that it resembles an addiction	a person who uses something or someone selfishly or unethically
	a person who takes drugs

addict (verb)	user (verb)
to cause (someone or oneself) to become dependent (on something, especially a narcotic drug)