What makes a horse 'handy'? When you come to a gate on a useful horse it will stand quietly while you get off and open the gate. When you come to the same gate on a horse that is handy you sidepass up to it, open it, ride through, then close it behind you.
A useful horse is good for gathering and penning cattle and will stand indefinately tied to the fence while you sort the cattle prior to loading them. A handy horse is also good for gathering and penning cattle but once penned you can easily ride in and sort and load the cattle quietly and efficently.
Basically, when a horse is handy nobody notices his presence because the rider isn't yanking and cussing or letting the cows run past or knocking down jumps or wrecking carts.
Ray Hunt is the one that first got me thinking about the distiction. He said that if all he used a horse for was to ride to the mailbox and get the mail he would have a horse that was handy to do it on. He also said that the way to get there was to understand how to set a horse up to help it do what you wanted instead of getting in the way and making the horse do it in spite of you.
So is your horse handy or useful and do you care?