I think why jogging is completely different to using cardio machines is that the machines (such as cross trainer and bike) support your body weight.
When jogging, your body is forced to support itself and you have to "carry" your own weight. Also, jogging outside is again different to jogging on a treadmill because it forces you to actually propel yourself forward whereas on a tready you just move your legs and the ground is moving beneath you. That's why they say to always jog on a level one incline on the treadmill so it makes you push forward so as to simulate outdoor jogging. I hope that made sense.