Energy is the thing which enables us to do useful work. We can categorise Energy into a number of different ways. So ChemicalEnergy is the Energy contained in a Fuel which we can release by Combusion. KineticEnergy is the Energy contained by some mass while it is moving. Heat is the Energy contained within matter which makes it appear warm.
Most Energy machinary that we use on a day to day basis converts Energy from one form to another. Pretty much always, then end up producing Heat. So, a car uses ChemicalEnergy in Petrol, uses a PetrolEngine to convert it to KineticEnergy which in turns ends up as Heat in the breaking system.
The word Power and Energy are often used interchangably with each other. Hence, we have GeoThermalEnergy, but WindPower. They are actually different though. Power is the rate at which Energy is transformed to useful Work.