Canvasback (Male)

Karen, the best way to tell the two apart is by the coloration of the bill (on the Redhead the bill is blue like the two Scaup sp. and black on Canvasback) and the back color (Redhead's is gray while the Canvasback's is white).

It's easy to confuse the male Redhead duck and the male Canvasback. I just look at the smooth transition from head to bill on the Canvasback compared to the definite transition from head to bill on the Redhead.