You should not be using leverage with either of them, but with the draw reins, very few people don't don't use force. You can always tell when a horse has been ridden in draw reins, the curve of the neck is broken. This doesn't seem to happen with running reins, mainly because you can't get the horse in the artificial very low head carriage that you see with the draw reins.
The running rein goes through the bit rings and to the top of the girth/girth straps, which is a different action on the bit, head and neck.
Side reins are fixed, saddle to bit, but with the running reins, you can play with the bit and encourage the horse to drop his nose.
A rider that has an independent seat and doesn't hold on by the reins, can use the running reins to a good effect, but with the draw reins, all you do is pull the head down.
The running rein goes through the bit rings and to the top of the girth/girth straps, which is a different action on the bit, head and neck.
Side reins are fixed, saddle to bit, but with the running reins, you can play with the bit and encourage the horse to drop his nose.
A rider that has an independent seat and doesn't hold on by the reins, can use the running reins to a good effect, but with the draw reins, all you do is pull the head down.