The lesser scaup and ring-necked duck are two species of diving ducks that are similar in appearance. Both species have dark brown bodies and white underparts. The lesser scaup is slightly smaller than the ring-necked duck, and the male lesser scaup has a black head, while the male ring-necked duck has a dark brown head. Female lesser scaups and ring-necked ducks have similar plumage, but the ring-necked duck has a white ring around its neck, while the lesser scaup does not.
Both species of ducks are found in North America, and they migrate south for the winter. The lesser scaup is found in a wider variety of habitats than the ring-necked duck, and it is more common in the western United States. The ring-necked duck is more common in the eastern United States, and it is also found in Europe and Asia.