Down comes from the undercoat of specific birds, and the undercoat is not considered feathers. In addition, you can find down in varying grades, based on the type of bird and its age from which the down was taken.
The Down Difference
Grown around a central quill minus the hard shaft, down, which resembles the fluffy top of a dandelion, comes from the undercoating of waterfowl, such as geese and ducks. This down undercoating keeps waterfowl warm because its structure traps air in pockets to create an insulating barrier. Land-based birds typically do not produce down. The properties of down -- soft, light and warm -- make it an ideal choice for pillows, comforters, sleeping bags and insulated clothing.
Waterfowl grow three basic feathers in addition to their down undercoat. The feathers they grow include body feathers and large and small flight feathers. The larger the feather, the harder the quill shaft. When waterfowl feathers are used in pillows, they are not as soft as down pillows.
The highest quality down comes from the eider sea duck, an endangered and protected bird. The down has superior insulating qualities, is lighter and warmer compared to down from geese or other ducks, and must be hand-collected from nests, which contributes to its cost. The female eider duck plucks the down from its own breast to make its nest.
Down and Feather Quality
The down undercoating and the feathers from the bird are graded based on several factors. For the most part, the highest quality down comes from the large, mature birds. Down taken from smaller, immature birds collapses more quickly and doesn't provide the warmth of higher quality down. Generally -- except for eiderdown -- goose down is of higher quality than duck down.
Down and Feather Pillows
Examine the label carefully, as some pillows labeled down may actually be made from small flight feathers. Down -- except for eiderdown -- is taken from birds raised for poultry purposes. After plucking, the down and feathers are washed and separated into various grades by a blower. The process of cleaning and grading the down and feathers ensures the fluff or loftiness of the feathers and the down.
Feather pillows do not have the loft or fluff of down because of the flattened quill shaft that adds weight to them. Because of this, feather pillows flatten more quickly than down pillows. The quills are not removed from the feathers, which may cause them to poke right through the fabric used to make the pillow.