I sometimes see people who aren't accustomed to drawing the structure of ungulate legs make them bend the way that canine legs and such do, so i sketched this up. It could have been done better, but ah well. I hope it is helpful.

Hooved animals are literally walking on the tips of their 'fingers' (hooves are basically fingernails!) whereas pawed animals walk on their entire fingers. The bones between joints 2 and 3 in my diagram are equivalent to our metacarpals, or the long bones in the back of our hand. While people might refer to joint 2 on a horse as his 'knee' it equates to his wrist, in terms of relative anatomy.
Yeah, dunno how to describe it better than that, but i think that's fairly clear. XD

EDIT: Oops, i meant to put this in scraps! There.