I'm not sure about the caloric difference, but I would think that fitness wise, walking in a forward motion (moving) is better than walking in place (stationary). The physics change a bit when you're propelling your body forward, which in my mind would require exerting more energy.
I think especially for anyone walking outside, the incline of the path changes, the elements (wind in your face, for example) can be more challenging, and therefore you will get more out of moving than staying stationary. And if your body is exerting more energy, you're also in turn going to be burning more calories.
This is just purely my opinion though, as I don't know of any actual studies that have been done on this.