Potential energy is stored energy. Kinetic energy involves movement.
If a ball is on the top of a hill, it has the most potential energy on the very top of the hill. The kinetic energy is also 0 at this point.
If the ball rolls down the hill, potential energy decreases while kinetic increases.
simple example
Well if the change is reversible then it is a physical change, but if not then it is a chemical change.
