footwear vs overshoe

footwear and overshoe both are nouns.

Word	Noun	Adjective	Verb	Adverb
footwear	Yes	No	No	No
overshoe	Yes	No	No	No

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

Other hyponyms of footwear include boot, clog, geta, patten, sabot, flats, shoe, carpet slipper, slipper.

footwear (noun)	overshoe (noun)
covering for a person's feet	footwear that protects your shoes from water or snow or cold
clothing worn on a person's feet