Bethel, I think the differences between the two are going to be insignificant for your purposes. Do the one you enjoy the most and keep on pushing yourself. (Your heart rate will adapt).
Tonia, you want to exercise between 60% and 80% of your maximum heart rate. (To get a reasonable estimate of your max, subtract your age from 220). More importantly, you want your heart rate to be as high as you can sustain for the length of your workout. The whole 'fat zone' thing is a myth--more calories are burned by working harder and having a higher heart rate. So, push yourself and work hard, but not so hard that you hurt yourself or burn out.