Stop. Don't run. Stand still, and let it go on its way.
Give it plenty of space.
Never stare an animal down. It considers that a threat.
Considering that most coyotes aren't much bigger than foxes, I don't see how they're being treated as such a booger. I doubt that any coyote who encountered a human (an adult, anyway) would stay around very long.
15 lbs is big for a red fox. 12 lbs is more like it. They look larger because they have a lot of hair and the hair fluffs.
A coyote that is equivalent to the 15 lb. red fox will weight 40 lbs.
But equally signigicant, the red fox is a loner. Except when the vixen is teaching her cubs to hunt or during breeding season, you will almost never see two fox toghether.
Coyotes on the other hand will pack up into large packs. Four or more 40 lb agressive animals with long sharp teeth can do a lot of damage.
Also fox are afraid of almost everything. Coyotes are much more clever about what they can get away with.
The coyotes we have here in central Alabama are considerably larger than a fox. In fact, some of them are way more than 40 pounds. I have a feeling that they are cross breeding with wolf hybrids that people let loose. We shot one last year that was 70 pounds. It was definitely a coyote. They reek havoc with livestock. I've got two Great Danes to watch after me when I'm outside doing chores.
About a year ago, in Marquette, MI, a teenaged boy was walking home after his four-wheeler quit on him. Coyotes began stalking him. One was bold enough to get close enough for him to whack it with his helmet.