What is the difference between aerobic and anaerobic respiration?

Both aerobic and anaerobic respiration have glycolysis as their first steps. Glycolysis occurs in the cytoplasm and involves phosphorylation of glucose to glucose-6-phosphate, forming ATP and reduced NAD. Pyruvate is then formed by breaking glucose-6-phosphate in half.Once pyruvate is formed, the process has one of two fates. Aerobic respiration occurs in the presence of oxygen, anaerobic respiration occurs when oxygen is absent. During aerobic respiration, pyruvate undergoes oxidation-reduction reactions to form carbon dioxide and more ATP. During anaerobic respiration, pyruvate is converted to ethanol or lactate and reduced NAD is oxidised. This oxidised NAD can then return to glycolysis and produce more ATP.