What is the difference between aerobic and anaerobic respiration?

It is important to first understand the concept of respiration. It is not the same as ventilation (breathing), as respiration is a chemical process that involves the breakdown of basic chemical molecules to release energy. 

A simple way of defining aerobic and anaerobic respiration, is that aerobic involves oxygen whereas anaerobic doesn't. 

Aerobic respiration

A general equation for aerobic respiration is C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O. As you can see in the equation, oxygen is needed for this reaction. This reaction results in a large energy production in the form of ATP to supply the cells in your body. It normally occurs in the mitochondria of cells and is the main type of respiration that you use every day.

Anaerobic respiration does not require oxygen and only produces a small amount of energy compared to aerobic respiration. In humans, It can be defined by this equation: C₆H₁₂O₆ (glucose)→ 2C₃H₆O₃ (lactic acid) 

Due to lactic acid build up, anaerobic respiration is not sustainable in the long term. If too much lactic acid accumulates, the cells become too acidic and can be damaged. Lactic acid must be oxidised back into pyruvate or to the liver to be processed. 

Anaerobic respiration normally happes when you need a fast supply of energy e.g. when you are in a sprint