Calories
A calorie is a unit of energy often used in nutrition to quantify the energy content in food. Specifically, one calorie (cal) is defined as the amount of energy required to raise the temperature of one gram of water by one degree Celsius at a pressure of one atmosphere.
Calories (Kilogram,mean)
The kilogram calorie sometimes referred to as a "large calorie" or "food calorie" is the energy required to raise the temperature of one kilogram of water by one degree Celsius at one atmosphere of pressure.