1. It takes place in living cells only.
2. It is carried out with the help of various enzymes.
3. The oxidation of food and the liberation of energy occur in a step-wise manner.
4. It occurs at the body temperature of the organism.
5. 60% of energy escapes as body heat and 40% of energy is packaged directly into new chemical energy (ATP).
Combustion1. It does not take place in the living cell.
2. Enzymes are not involved in this process.
3. The substances are oxidized Spontaneously with sudden release of energy.
4. Sudden release of energy generates high temperature of a fire.
5. Energy released in combustion is dissipated as heat and to some extent as light.