When exerciszing, what are the benefits for staying in aerobic zone vs. Fat burning vs. Anaerobic?  

Red line Zone. Red line (maximum effort)- 90 - 100% of max heart rate. This zone burns the highest number of calories and is the most intense. This can only be sustained for short periods of time and one should only train in this zone if they are in a very good shape and have been cleared by a physician.
Anaerobic zone. Anaerobic zone (performance training)-80 - 90% of max heart rate. This zone results in improved vo2 maximum (the highest amount of oxygen one can consume during exercise) and thus an improved cardiorespiratory system, and a higher lactate tolerance ability which improves endurance and the ability to fight fatigue. Overall this high intensity zone burns more calories but only 15% from fat.
Aerobic Zone. Aerobic zone (endurance training)- 70 - 80% of max heart rate. The aerobic zone improves the cardiovascular and respiratory system and increases the size and strength of the heart. This is the ideal zone for an endurance event. Overall more calories are burned with 50% from fat.
Fitness zone. Fitness zone (fat burning)- 60 - 70% of max heart rate: this is a more intense version of the healthy heart zone and provides the same benefits. Overall more calories are burned but the percent of burned fat calories is still 85%.
Healthy heart zone. The five zones are as follows: healthy heart zone (warm up) is 50 - 60% of max heart rate. Easiest and best zone for starters of a fitness program. This zone has been shown to help decrease body fat, blood pressure and cholesterol. It also decreases the risk of degenerative diseases and has a low risk of injury. 85% of calories burned are fat. More to follow..................
All good. Honestly they are all good, and they all burn calories and fat. Those zones posted on exercise machines are not absolute. Exercise is good for you...Stay in a zone that challenges you, but don't stress about the chart.