Up here in Saskatchewan I would say in general a mule deer will weigh in 10% heavier than a whitetail. A mature whitetail buck here would average 250lbs while a mature mulie buck would tip in around 275lbs..this on the hoof. Of course they can be larger and smaller. Personally have seen several mule deer bucks would be well over 300lbs on the hoof and a number of whitetail bucks that would top the 300 line as well. I shot a mulie buck 8 years ago that we estimated would be 350 and 3 years ago shot a whitetail buck that we just had to weigh. FD he tipped the scales at 307 without any guts....so I'd say without question this buck was 350+ on the hoof.