bowler hat vs derby hat

bowler hat and derby hat both are nouns.

Word	Noun	Adjective	Verb	Adverb
bowler hat	Yes	No	No	No
derby hat	Yes	No	No	No

As nouns, bowler hat and derby hat are synonyms defined as:

bowler hat and derby hat: a felt hat that is round and hard with a narrow brim

Other synonyms of bowler hat include bowler, derby, plug hat.

bowler hat (noun)	derby hat (noun)
a felt hat that is round and hard with a narrow brim	a felt hat that is round and hard with a narrow brim