Potential energy is the energy which is stored in a body when a certain force is applied on a body or work done on it.
Stretching a rubber band or spring, punching a non elastic ball, binding a cracker with string. In this the energy is stored in the objects after applying force on them and when released it is converted to other forms of energy like kinatic energy, chemical energy or sound
Gravitational potential energy is the energy stored in the object when work is done or applied in opposition with the gravitational force acting on it. e. g. water stored in dam, ball thrown in air or an elevator going up.
Obviously gravitational potential energy is the subset of all potential energies stored in the body..