maillot vs swimming costume

maillot and swimming costume both are nouns.

Word	Noun	Adjective	Verb	Adverb
maillot	Yes	No	No	No
swimming costume	Yes	No	No	No

As nouns, swimming costume is a hypernym of maillot; that is, swimming costume is a word with a broader meaning than maillot:

Other hypernyms of maillot include bathing costume, bathing suit, swimsuit, swimwear.

maillot (noun)	swimming costume (noun)
tights for dancers or gymnasts	tight fitting garment worn for swimming
a woman's one-piece bathing suit