Potential Energy is the energy held by an object because of its position relative to other objects. It has the <em>potential </em>to move, but it hasn't yet. An example of this would be a ball at the top of the hill. It hasn't started rolling, but it definitely can!
Kinetic Energy is the energy that an object possesses due to motion. Once an object overcomes its inertia and friction (which requires energy), the object will continue to move and expend energy. An example of this would be a ball rolling down a hill.
