drinker vs sucker

drinker and sucker both are nouns.

Word	Noun	Adjective	Verb	Adverb
drinker	Yes	No	No	No
sucker	Yes	No	No	No

As nouns, sucker is a hyponym of drinker; that is, sucker is a word with a more specific, narrower meaning than drinker:

Other hyponyms of drinker include gulper, guzzler, quaffer, sipper.

drinker (noun)	sucker (noun)
a person who drinks alcoholic beverages (especially to excess)	mostly North American freshwater fishes with a thick-lipped mouth for feeding by suction; related to carps
a person who drinks liquids	an organ specialized for sucking nourishment or for adhering to objects by suction
	hard candy on a stick
	flesh of any of numerous North American food fishes with toothless jaws
	a drinker who sucks (as at a nipple or through a straw)
	a person who is gullible and easy to take advantage of
	a shoot arising from a plant's roots