duck:
The overall body plan of ducks is elongated and broad,and the ducks are also relatively long-necked,albeit not as long-necked as the geese and swans.The body shape of diving ducks varies somewhat from this in being more rounded.The bill is usually broad and contains serrated lamellae which are particularly well defined in the filter-feeding species.In the case of some fishing species the bill is long and strongly serrated.The scaled legs are strong and well developed,and generally set far back on the body,more so in the highly aquatic species.The wings are very strong and are generally short and pointed,and the flight of ducks requires fast continuous strokes,requiring in turn strong wing muscles.
goose:
Farm goose structure:upright posture and fat rear end
Wild goose structure:horizontal posture and slim rear end
Chinese geese may be readily distinguished from European geese by the large knob at the base of the bill,though hybrids may exhibit every degree of variation between them.
Chinese geese differ from the wild birds in much larger size,and in having an often strongly developed basal knob on the upper side of the bill.The knob at the top of the beak is more prominent on males than females.