canvasback vs. redhead

canvasback

noun

plural canvasbacks, (especially collectively) canvasback.
  1. a North American wild duck, Aythya valisineria, the male of which has a whitish back and a reddish-brown head and neck.

redhead

noun

  1. a person having red hair.
  2. an American diving duck, Aythya americana, the male of which has a bright chestnut-red head. heads.