On the Galaxies, the "KD" on the heel is supposed to be stitched. This is only on the Galaxies. Every other KD IV is plastic or some similar material. So the fakes just do a plastic KD on the heel.
Not shown in these pictures, but on fakes they put the inner label on the tongue. Authentics have the label on the side.
And of course you could always tell a fake if the strap and laces don't have 3M.