swimming trunks vs bathing suit

swimming trunks and bathing suit both are nouns.

Word	Noun	Adjective	Verb	Adverb
swimming trunks	Yes	No	No	No
bathing suit	Yes	No	No	No

As nouns, bathing suit is a hypernym of swimming trunks; that is, bathing suit is a word with a broader meaning than swimming trunks:

Other hypernyms of swimming trunks include bathing costume, swimming costume, swimsuit, swimwear.

swimming trunks (noun)	bathing suit (noun)
swimsuit worn by men while swimming	tight fitting garment worn for swimming