Both explode. I recently purchased some of the new Hornady 25 grain HP for my 17 Hornet. Previously all the factory ammo to be had for the 17 Hornet was 20 grain VMAX. So what is the walls of the bullet on the VMAX more thin and are more explosive than the HP?
Put ballistic tips in the argument!! The only difference is how do you like your should burger ground up, ruff, medium or fine ground. HP can be deceiving since x-bullets come in then and they certainly are not included in this discussion. It's jacket thickness and core bonding that's in question.