While all good for us, what are the benefits of aerobic, fat burning and anaerobic zones during exercise?

Durations, etc: Theoretically the fat burning zone is lower intensity, meaning you burn calories longer and go through the sugar and glycogen stores, allowing your body to start burning stored fat. This is typically an aerobic (with oxygen) process. Anaerobic zones are usually higher intenstity and faster, causing the body to work harder, but last shorter. This is good for building endurance and efficiency.

Different benefits: Aerobic and fat burning are the same; exercise that utilizes oxygen in the process of burning fat as a fuel. Anerobic exercise is exercise that does not utilize oxygen, typically in muscle building.