gym suit vs activewear

gym suit and activewear both are nouns.

Word	Noun	Adjective	Verb	Adverb
gym suit	Yes	No	No	No
activewear	Yes	No	No	No

As nouns, activewear is a hypernym of gym suit; that is, activewear is a word with a broader meaning than gym suit:

gym suit: clothes prescribed for wear while participating in gymnastic exercise
activewear: attire worn for sport or for casual wear

Other hypernyms of gym suit include athletic wear, sportswear.

gym suit (noun)	activewear (noun)
clothes prescribed for wear while participating in gymnastic exercise	attire worn for sport or for casual wear