Thermal energy is just a fancy word for heat energy. It’s a form of both potential and kinetic energy.
If you remember, the electrons of an atom have potential energy. Once you apply pressure to the electrons, they start to move rapidly, banging into each other, and releasing thermal energy as heat.
Think of boiling water for a bit. Water, when placed on the stove, has potential energy. But once it starts to heat, the water molecules begin to move faster, creating kinetic energy.
Thermal potential energy is potential energy at the atomic and molecular levels when the particles show the potential of converting into kinetic energy. On the other hand, thermal kinetic energy is when the atoms and molecules start moving due to heat and temperature.