Answer:
The kilogram (kg) is the SI unit for mass. Not weight.
So when you say « heavier » and mention kg, I would assume you’re talking about mass.
The mass of 1 kg of feathers and 1 kg ok bricks are identical.
And if you want an answer to your question comparing the weight on Earth of those 2 items, in vacuum of one kilogram of feathers would have exactly the same weight as one kilogram of bricks.
Step-by-step explanation:
Hope this helps! <3