Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize food from carbon dioxide and water, releasing oxygen as a byproduct, while respiration, on the other hand, involves the consumption of oxygen (in aerobic respiration) to break down food (glucose) and release energy, producing carbon dioxide and water as byproducts. The liberation of oxygen is unique to photosynthesis and differentiates it from respiration.