Fat burning or cardio - which is best

Hi.  I travel a lot - so when I do have time to exercise - it is usually in the hotel fitness room - which is limited in what is available.  However, there is usually a treadmill.  

What are the difference in benefits for sticking to the fat-burning vs the cardio workouts that are pre-programmed and go by your heart rate?  I do not run or jog - it is very hard to do with asthma.  However, I do walk and do the hills programs etc...at a max pace of usually about 4.5 or 5 with a max incline of about 7.  

Would there be something else that might give me more benefit.  I'm not really overweight but trying to tone up a bit.  I am 5'4" and weigh between 125 and 128 most days.  

I guess I'm confused on which programs are better b/c I see that the cardio ones burns so many more calories than the fat burning ones that I do - but one is labeled as "fat burning".

Can someone please explain.  I thought a calorie was a calorie.

[barn babe]

Forget about the "pre-programmed" stuff on the 'mills. Set up your own high-intensity workout based on your current fitness level. You can increase the grade and the speed as you get more fit, or as your asthma allows.  

You said you are walking at a 7% grade. Is that the easy end for you, or the difficult end? Basically, you want two "ends" that you work between: a high end, which should be enough for you to really feel it, so if that's 7%, set it there with a speed that kicks your butt. Then you want a low end to come back down to, which can be half of that, or about 3-4% at a slower speed. Do the 7% grade for 2 minutes, then drop to the lower level for 1 minute to recover. Then ramp back up to the high or 7% grade for 2 minutes, ramp back down for 1 minute to the lower level. Do it 10 times, or for 30 minutes.  

Here's an example that I personally use: I set it at a 10% grade at 7 mph. I do that for 2 minutes. I ramp it down to 3 mph, still at 10%. I do that for 1 minute. I ramp it back up to 7 mph and do it for 2 minutes, then back down again for 1 minute. I do that for 30-35 minutes or so.

The other thing you can do if you have access to dumbbells takes only 4 minutes, and you will put yourself into a killer fat burning zone metabolically with this:  get the heaviest dumbbells you can manage.  Face a large wall clock with a sweep second hand. Hold the dumbbells on your shoulders, in the same position as if it  were a barbell (or find a barbell if you can handle the weight).  Now do squats as quickly as you can for 20 seconds. Watch the clock. Come up and rest for 10 seconds. Do another set of squats for 20 seconds. Rest for 10 seconds. Do this for 4 minutes total. You won't believe the burn you'll get from this. It's killer. Trims up the thighs and hips like nothing else.