footgear vs flats

footgear and flats both are nouns.

Word	Noun	Adjective	Verb	Adverb
footgear	Yes	No	No	No
flats	Yes	No	No	No

As nouns, flats is a hyponym of footgear; that is, flats is a word with a more specific, narrower meaning than footgear:

Other hyponyms of footgear include boot, clog, geta, patten, sabot, overshoe, shoe, carpet slipper, slipper.

footgear (noun)	flats (noun)
covering for a person's feet	footwear (shoes or slippers) with no heel (or a very low heel)