I live in Western Kansas where we have primarily mule deer. Actually that's all I've ever taken before this year (this was my first year with a bow and I shot a whitetail). I've stalked mulies in wide open prairie pastures but the closest I've ever been able to get is about 50 yards which is more than I ever needed with a rifle. In our terrain I think a muley would be more difficult because the big boys are always out in the open and rarely do you see them around cover like trees. I used to think the whitetails were harder because they are much more skitish. I think that if you put the two deer in the same situation such as acreek bed with some trees and brush the muley would hands down be the easiest because they tend to stand & stare for longer than a whitetail thus presenting you a shot.
I honestly believe that you can pattern mule deer to some extent even though it's not as set in stone. Of all the big muleys I've seen taken with a bow it's really a matter of being in position at the right time because you new the general area that they ran and where you thought you could get closest to them. It's not necessarily a matter of bucks feeding in a foodplot, or a buck chasinga doe in an alfalfa field near your stand. My friend shot a monster muley last year while crouching on an old bridge. He new the buck was in the general area and happened to see him moving from a long distance and got to the bridge in time to set up before the buck came under.
All this applies to our area where it's primarily our cattle pastures and the only cover is yucca plants. My buddy shot this buck this year which I thought was pretty nice.
Ty