Fat Girl Fatburn versus Cardio Zone

My Question: When I choose the weight loss program on any of the machines at the gym I notice that not only is there a fat-burn zone but a cardio zone, whats the difference?

Answer: When you stay in your fat burning zone 50% of the calories you burn are fat, in the cardio zone only 40% of your calories burned are fat calories.

Question: So which one is better?

Answer: Lets say you get on the stair master for 30 minutes and stay within the fat burn zone. Easy Peasy, you've burned about 200 calories, so 50 % of that, 100 calories were fat. 

in comparison too ...

30 minutes on the stair master in the cardio zone, panting like a dog on a hot summer day, and pouring sweat. Since I have yet to try that we will say you burned 400 calories. 40% of your calories burned 140 calories are from fat.

Hmmmm, 100 calories of fat in fat-burn zone or 140 calories of fat from cardio zone? Wonder which one I should pick?