Define the work and energy
Work is said to be done when a force produces a displacement in the body and acts in any direction except perpendicular to the direction of displacement.
Work = Force×Displacement
When a body moves up, work is done against the gravity.
When the displacement is perpendicular to the gravitational force(force acting in downward direction), then the work done by the gravitational force is said to be zero. For example:- As an object moves on the earth(horizontal plane), then work done by the gravity is zero.
Energy is the ability to do work. It's unit is Joules (J).
Energy obeys the conservation law that it cannot be created or destroyed but only changed into its different forms. Some different types of energy are Heat Energy, Kinetic Energy, Sound Energy.
For example, while playing a game of billiards if a player hits a stationary ball with the cue stick the mechanical energy provided by him/her converts into kinetic energy as the ball now moves a certain velocity.