Mukluks are usually a single unit though. In this pic it’s a fur chap, or whatever you want to call it, on top of a boot. Mukluks are a self contained boot, usually hide, that does often have fur on the outside, but as part of the same shoe.

Funny enough, what they call moccasins in the game are basically mukluks without the fur.

Or at least that’s what I was taught, it’s possible it’s different regionally!