The difference in outcome between the potential energy in a marshmallow burned over a campfire on the end of a stick and in one that you eat straight from the package is

How fast and efficient the energy is released.

Explanation:

Before burning the marshmallow energy is stored in it in the form of chemical bond energy or chemical potential energy. So upon burning this energy is released. So there will be a difference in energy release from a burned marshmallow and the one we eat straight from package.