What is the difference between a duck and seagull?

Seahawk: The Osprey (Pandion haliaetus) is a diurnal, fish-eating bird of prey. It has been given its own taxonomic genus, Pandion and family, Pandionidae. It is a large raptor, reaching 60 centimetres (24 in) in length with a 2 m wingspan.

Seagull: Gulls are birds in the family Laridae. They are typically medium to large birds and range in size from the Little Gull, at 120 g (4.2 oz) and 29 cm (11.5 inches), to the Great Black-backed Gull, at 1.75 kg (3.8 lbs) and 76 cm (30 inches).