I'm no expert in POL, but from what I've picked up in my time in, the air force uses
JP-8, the navy uses
JP-5 and the army runs diesel in all of their equipment, the M-1, Hummer's, Bradley's, etc, in order to simplify the logistics chain. Way back when,
JP-4 was used by the air force, but sometime along the line it switched to
JP-8, don't know what the different additives are, but I do know that
JP-8 smokes a bit more.
Now how all this works out when
USN aircraft take fuel from
AF tankers, I don't know, I'm guessing they can run on either, and it's just a matter of prefrence of that service branch.