bowler hat vs plug hat

bowler hat and plug hat both are nouns.

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

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

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

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

bowler hat (noun)	plug 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