What is the difference between aerobic and anaerobic respiration?

So respiration is the means by which all cells produce energy, and this is done through aerobic or anaerobic respiration of glucose. Let's concentrate on animal cells first.

Anaerobic respiration occurs in the cytoplasm of the cell, so in the main body. This process happens in the absence of oxygen and is a very quick method of producing small amounts of ATP, which is a very energy-rich molecule which cells use to transport and store some energy. However, in the process of forming this ATP, lactic acid is produced, which can build up and become toxic. This has to be removed later on when oxygen is present. In plants and other life forms this process can differ slgihtly.

Aeorbic respiration occurs in the presence of oxygen and has some similar elements to anaerobic respiration. However, the products of the reaction then get fed into a cycle of further reactions, known as the Krebs cycle (or citric acid cycle, or TCA cycle). This takes a while longer than the anaerobic respiration step but produces a lot more ATP, so allows a lot more energy to be drawn from the glucose molecule. The individual steps of the Kreb's cycle can be complex but can be broken down into manageable portions depending on the syllabus requirements.