The only use I can think of is that they are processed and transformed into a plastic like substance and plastic products are actually made from them. Down pillows, or feather pillows usually contain goose feathers. What the real difference is I'm not sure.
You mean like pillows and dolls? In my country we use something called dacron (white substance like cotton).
turn chicken feathers into thermoplastics
Mostly for stuffing.
To make pillows?