In a vacuum, both heavier and lighter objects fall at the same rate due to gravity, which accelerates them equally despite their mass differences. The force of gravity is stronger on heavier objects, but their greater mass means they require more force to achieve the same acceleration as lighter objects. This results in both types of objects experiencing the same acceleration when falling. The discussion emphasizes the importance of understanding the relationship between mass, force, and acceleration, as described by Newton's laws of motion. Ultimately, the conclusion is that gravity's effect is consistent across different masses, leading to identical fall rates in a vacuum.