running suit vs athletic wear

running suit and athletic wear both are nouns.

Word	Noun	Adjective	Verb	Adverb
running suit	Yes	No	No	No
athletic wear	Yes	No	No	No

As nouns, athletic wear is a hypernym of running suit; that is, athletic wear is a word with a broader meaning than running suit:

running suit: a matching jacket and pants worn by joggers and made of fabric that absorbs perspiration
athletic wear: attire worn for sport or for casual wear

Other hypernyms of running suit include activewear, sportswear.

running suit (noun)	athletic wear (noun)
a matching jacket and pants worn by joggers and made of fabric that absorbs perspiration	attire worn for sport or for casual wear