What is the relationship between heat of combustion and calorific value?

Heat of combustion: At 25 degrees Celsius and 101 kPa, the heat released when 1 mole of a combustible substance burns completely to form stable compounds is known as the heat of combustion of that substance. Calorific value: also known as calorie value or heat content. In fuel chemistry, it is an important indicator representing the quality of fuel. The heat released when a unit weight (or volume) of fuel is completely burned. In food chemistry, it is an indicator of the energy content of food. It refers to the heat released when 1 gram of food is oxidized in the body. I hope you understand now after reading this

Heat of combustion: At 25 degrees Celsius and 101 kPa, the heat released when 1 mole of a combustible substance burns completely to form stable compounds is known as the heat of combustion of that substance. Calorific value: The heat released upon burning a unit weight of a substance. (Usually referring to 1 KG) According to available information, calorific value is further divided into net calorific value and gross calorific value. Net calorific value (also known as lower calorific value): It is the amount of heat released when a substance is completely burned and then cooled back to its initial state (ambient temperature), with the water vapor in the combustion products remaining in gaseous form. Total calorific value (also known as high calorific value): It is the heat released when a substance is completely burned and then cooled back to its initial state (ambient temperature), with the water vapor in the combustion products condensing into water. The original poster can see the difference from the above definitions.

Heat of combustion: At 25 degrees Celsius and 101 kPa, the heat released when 1 mole of a combustible substance burns completely to form stable compounds is known as the heat of combustion of that substance. The concept of combustion is broad in scope, but it usually refers to the heat of combustion that occurs when a combustible substance reacts with O2. Calorific value: Also known as the heat content or energy value. In fuel chemistry, it is an important indicator representing the quality of fuel. The heat released when a unit weight (or volume) of fuel is completely burned. There are two types: high calorific value and low calorific value. The former is the total of the heat of combustion of the fuel and the heat of condensation of water vapor, that is, the total amount of heat released when the fuel is completely burned. The latter is merely the heat of combustion of the fuel, that is, the difference between the total heat and the heat of condensation. In food chemistry, it is an indicator of the energy content of food. It refers to the heat released when 1 gram of food is oxidized in the body. The two differ in terms of definition and reaction conditions

These 2 parameters are commonly used in gasoline, diesel, or petroleum additives