Powder Absorptivity & Solid Absorptivity

What is the difference between the material properties "Powder Absorptivity " and "Solid Absorptivity " in Additive Print? Which material property controls the thermal influence of the un-melted powder?

Powder absorptivity is due to inter-particle reflections when it is in powder form whereas solid/liquid absorptivity is meaningful when the powder melts and solidifies.

For more details, please refer to the attachment below-