ANSWER:
Aerobic respiration will occur when there is presence of oxygen. This oxygen breaks down the glucose down all the way to carbon dioxide which can produce almost 38 molecules of ATP and so aerobic respiration releases more energy.
Step-by-step explanation:
Anaerobic respiration will occur when there is absence of oxygen. This respiration can break glucose into only two molecules of pyruvate. This is sufficient to produce only "two molecules of ATP". This amount of energy released is much less as compared to aerobic respiration.