Down: consists of clusters of filaments growing from a central quill point without a quill shaft. It looks much like a dandelion pod. Down is the light, fluffy undercoating that geese, ducks, and other waterfowl have to keep them warm. Its three dimensional structure allows it to make thousands of air pockets, which insulate incredibly well.
Land fowl such as chickens and sparrows do not produce down.
Along with down, water birds grow several types of feathers.

  Small flight feathers: are found among the larger flight feathers and form part of the flying surface of the wing. They are quite small and found on the wing and tail area of the bird.

Larger flight feathers: are straight, flat feathers with a hard quill shaft running from one end to the other with a series of fibers joining together into a flat structure on each side of the shaft. These feathers are found on the wings and tail. They are often chopped up to use in lower quality pillows and featherbeds.

  Body feathers: are grown primarily for protection. These feathers are found over the entire body of the bird. Body feathers have a bend or curve to the shaft giving them a spring which makes them suitable for use in featherbeds and feather pillows.