Comp said all that needs to be said. A drag bunt is exactly that - feet are moving forward, bat has no swing in it. Why? Because it's a drag BUNT.
That is one reason why a slap-bunt is a deadly weapon. It is not a drag. They slap at the ball but stop the bat right before impact and just tap it. It is not a soft-slap and it is not a drag bunt. It is a slap with a bunt result. Tough for the umps to call that a bunt.