Final answer:
The difference between the molecules of the heated and unheated potatoes is that the heated potato has molecules with increased kinetic energy, causing a higher temperature.
Step-by-step explanation:
The difference between the molecules of the two potatoes can be explained by the kinetic-molecular theory. When Bree put her potato in the campfire, the heat from the fire increased the kinetic energy of the molecules within the potato. This means that the molecules are moving faster, resulting in a higher temperature for the potato. In contrast, Rico's potato, which was not heated, has molecules moving at a slower rate, thus maintaining a lower temperature.