Energy conservation is any behavior that results in the use of less energy.
Energy efficiency is replacing inefficient equipment or appliances with a similar device that uses less energy to perform the same function or task with the same degree of performance or service.
For example: turning a light off is energy conservation while replacing a CFL bulb with a more efficient LED is an energy efficiency measure.
Energy tip: The least expensive energy and the most environmental benefit is the energy not used. When something is not in use turn it off. Start hitting that off switch today!