This means that the earth pulls 50 times as hard on the coin as it does on the feather. You might think this would cause the coin to fall faster. The two effects exactly cancel out, and the two objects therefore fall with the same acceleration. This rule holds true only if gravity is the only force acting on the two objects. If the objects fall in air, then air resistance must also be taken into account.
Larger objects experience more air resistance.
Also, the faster an object is falling, the more air resistance it feels. Since the feather is so much lighter than the coin, the air resistance on it very quickly builds up to equal the pull of gravity. After that, the feather gains no more speed, but just drifts slowly downward. The heavier coin, meanwhile, must fall much longer before it gathers enough speed so that air resistance will balance the gravitational force on it. The coin quickly pulls away from the feather.