If we assume there is no air resistance, the only value that will be different for the hammer and the feather is:
the upward push of air resistance
Since we’re considering a vacuum scenario (no air resistance), both objects would fall at the same rate and hit the ground at the same time regardless of their mass. Therefore, no differences would be observed in the gravitational attraction, the time it takes to fall, or the velocity—all would be the same for both objects. However, in the presence of air, the feather would experience a significant amount of air resistance, while the hammer would not. In your scenario of no air resistance, this question becomes moot because there would be no upward push of air resistance acting on either object.
In a complete air resistance-free scenario, the correct answer is technically not applicable since they would have no air resistance acting on them, but if you meant to imply a comparison with a scenario including air, the air resistance would be the key differing factor.