They differ in the sense that it's easy to imagine how you can reclaim the energy in the stone -- let it roll back down the hill. It's harder to imagine how yo

They differ in the sense that it's easy to imagine how you can reclaim the energy in the stone -- let it roll back down the hill. It's harder to imagine how you can reclaim the energy of the computation. Overwriting a bit requires a little energy even in principle, and then you can't get it back. Maybe this is what the commenter I was replying to meant by "all energy generated ends up as heat." Even still, I'm tempted to make the distinction between the energy that is needed to perform the computation and the energy that is lost e.g. to Joule heating.