sewer vs tacker

sewer and tacker both are nouns.

Word	Noun	Adjective	Verb	Adverb
sewer	Yes	No	No	No
tacker	Yes	No	No	No

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

Other hyponyms of sewer include baster, sewing-machine operator, tucker.

sewer (noun)	tacker (noun)
a waste pipe that carries away sewage or surface water	a hand-held machine for driving staples home
misfortune resulting in lost effort or money	a sewer who fastens a garment with long loose stitches
someone who sews	a worker who fastens things by tacking them (as with tacks or by spotwelding)