There is a lot of confusion about this, and I would like you to help me to clarify my mind about this topic.
A system's internal energy can be the sum of all other forms of energy. Potential energy due do mollecular interactions, chemical energy, latent energy, kinetic energy of particles, etc. But, what about thermal energy? My way of understand it, is that Thermal Energy is just a "transducer" of the kinetic energy of particles. There is, manifestly, kinetic energy, because we know particles are moving, and "thermal energy" is just another way of saying that particles have kinetic energy, AND, with more Kinetic energy, there is more "thermal energy", and there will be more "Temperature".