For some reason on my client, it can't remove the spoiler (gives a network error). I'm assuming it says that since the ball has more mass, it has a higher attraction rate of its own gravity to Earth's, so does fall faster in a vacuum but so miniscule it would be hard to measure?
"The bowling ball isn't falling to the earth faster. The higher perceived acceleration is due to the earth falling toward the bowling ball." is what the spoiler says