What is warmer a goose or duck down jacket?

If you are talking about the warmth of a duvet it really doesn't matter which feather you use but depends on the tog rating of the one you have. The higher the tog the warmer the duvet. Most feather duvets come with either feather & down, or just down, the F&D are about 65% feather and 35% down. with these you get the 65% of feathers that may contain the stalks and the 35% down may contain the immature nestling feathers in them. With the down duvets you get 85% down and 15% nestling feathers. (please note: these percentages will be different for each manufacturer).

Down is warmer than feathers, duck down is superior to goose, and the Eider duck has the best down of all. This is why the comforter (US) is called an "eiderdown" in the UK. The name duvet comes from the French Word for down. Another name is "dyne" or Doona (pronounced dewner) which comes from Scandinavian languages. It can also be called a continental quilt or blanket.