Both are "breathing" functions, but fermentation does so without oxygen. respiration occurs with oxygen.
1. Both are bilogical oxidation reactions.
2. Respiration biological process which means complete oxidation of the reduced substrate to carbon dioxide and water.
3. Fermentation is also a biological process of substrate oxidation but incompletely. The products of fermentation are acetate, lactate, carbondioxde, etc.
1. Respiration yields more energy, while fermentation provides less energy.
2. Respration is an aerobic process, while fermentation occurs under anaerobic conditions.