Energy efficiency is using energy wisely.

In other words, you want to achieve the same results but you want to use less energy to do it.

For example, you want to keep your food cool, but you want to use less energy to do it. The solution is to use an energy-efficient refrigerator.

Energy conservation is using less energy.

In other words, you want to conserve energy so you change your behavior to use less energy.

There are lots of things you can do to use less energy. For example, you might turn off machines that you’re not using or replace all your light bulbs with more efficient ones.