When we drop a feather and a heavy stone at the same time from a height, they do not reach the earth at the same time. Why?

A buoyant and frictional force was applied on the feather due to air and so it floats and reaches the ground slowly, much after the heavy stone. Meanwhile, the buoyant and frictional forces on the stone is also much less than the weight of the stone and so does not affect the speed of the stone mulch. Scientists had performed this experiment in vacuum and showed that the feather and stone indeed reach the earth at the same time.