Calories (nutritional)
A nutritional calorie, specifically a kilocalorie (kcal), is the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius. In nutritional contexts, the term "calorie" typically refers to a kilocalorie.
Kilojoules
A kilojoule (kJ) is equivalent to one thousand joules (J). It is the energy required when a force of one thousand newtons is applied over a distance of one meter, or one newton applied over a kilometer. In reality, a joule is roughly the energy required to lift a small apple one meter against Earth's gravity.