drug user vs tripper

drug user and tripper both are nouns.

Word	Noun	Adjective	Verb	Adverb
drug user	Yes	No	No	No
tripper	Yes	No	No	No

As nouns, tripper is a hyponym of drug user; that is, tripper is a word with a more specific, narrower meaning than drug user:

drug user: a person who takes drugs
tripper: (slang) someone who has taken a psychedelic drug and is undergoing hallucinations

Other hyponyms of drug user include addict, head.

drug user (noun)	tripper (noun)
a person who takes drugs	a catch mechanism that acts as a switch
	a tourist who is visiting sights of interest
	a walker or runner who trips and almost falls
	(slang) someone who has taken a psychedelic drug and is undergoing hallucinations