trawler vs fishing boat

trawler and fishing boat both are nouns.

Word	Noun	Adjective	Verb	Adverb
trawler	Yes	No	No	No
fishing boat	Yes	No	No	No

As nouns, fishing boat is a hypernym of trawler; that is, fishing boat is a word with a broader meaning than trawler:

trawler: a fishing boat that uses a trawl net or dragnet to catch fish
fishing boat: a vessel for fishing; often has a well to keep the catch alive

Other hypernyms of trawler include fishing smack, fishing vessel.

trawler (noun)	fishing boat (noun)
a fishing boat that uses a trawl net or dragnet to catch fish	a vessel for fishing; often has a well to keep the catch alive
a fisherman who use a trawl net