fisher vs troller

fisher and troller both are nouns.

Word	Noun	Adjective	Verb	Adverb
fisher	Yes	No	No	No
troller	Yes	No	No	No

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

Other hyponyms of fisher include angler, trawler.

fisher (noun)	troller (noun)
large dark brown North American arboreal carnivorous mammal	a fisherman who uses a hook and line
someone whose occupation is catching fish