In terms of price, the price of down is much higher than that of down cotton. Duck down belongs to high-grade consumer goods.
The warm-keeping performance of duck down is much better than that of down cotton, but if it is used for too long, it will smell, while down cotton will not.
Although duck down has a good warm-keeping performance, once it is washed enough times, its warm-keeping performance will be reduced, even worse than down cotton. However, eiderdown cotton will not become less warm after washing.
If you wash it too many times, another situation may occur, that is, it will be hairy, but down cotton will not.