>>134894121kg of feathers is heavier because of the air trapped inside. 1kg of feathers is not very dense and therefore will occupy about 770cc. Meaning there will be about 0.9 grams of air in the interstitial space. So if you have 1kg of uncompressed feathers, it comes with 0.9 grams of air. Meaning the 1kg of feathers is heavier.
If you compressed the feathers, both would be equal.
