Kilowatt-hours
A kilowatt-hour (kWh) is the amount of energy when a power of one kilowatt (1,000 watts) is used continuously for one hour. Utility companies often bill consumers based on the number of kilowatt-hours consumed.
Calories (Kilogram,I.T.)
The kilogram calorie is often referred to as the kilocalorie or Calorie with an uppercase 'C'). It is defined as the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius at one atmosphere of pressure.