The distance shown in the diagram is know as the

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.