So we look at photons and we say here's a particle and here's a wave. It has these two natures. It is a particle sometimes and a wave other times. It's a particle and a wave depending on how you look at it. Light is not just a quantum, not just a packet of probabilities.
Light is also a qualum.
It contains both quantity and quality, so you have both a quantum and qualum aspect. Qualum mechanics is something we're inventing here. Nobody knows that yet. When we look at light in quantum mechanics, we can look at quantity in two ways. We can describe its mass and we can describe its energy.