Even well pelted coyotes look pretty mangy. Right now they are growing in their winter fur so they look rather ratty, especially if there are burdocks and cottontails around. Fur is typically cream to greyish brown, but they do have varying color phases. The size you describe is right, but a big bad predator often looks bigger than they really are. Tracks will look like a medium dog track, fox tracks look more cat-sized.
What was the body language? Coyotes tend to keep their tail low like a whipped puppy unless interacting with other canines. They're usually quicker to bolt than a fox. Gait is more running like a dog, a fox is bouncier. Foxes generally hold the tail straight out and will look at you a second before bolting (curiosity kills more than cats!).
Red fox are easy to spot, classic fox look except for "samsons" which is a drab, greyish reddish brown color phase. Greys are grey tipped with rust and blacks with a black tail tip. They are smaller than reds about the size of a large cat. Both will often stick close to cover, moving from bush to bush like a cartoon fox.
A #2 bridger foothold cross staked in a dirthole will be hell on either. So will a 17 HMR.
