and can be described as an electron falling to the empty hole state and filling it, emitting radiation.

However, there are also limitations to this analogy. Due to the symmetries of Dirac's theory, positron and electron have exactly the same mass, while holes and electrons in crystals generally have different masses. The positron is a real particle with positive inertial mass and rest energy, while the hole is a quasiparticle whose inertial mass is negative. For this reason the responses differ