I haven’t even looked at the hair in paragon so don’t consider this an informed opinion but perhaps they just had separate geometry with a different material.
along similar lines maybe different parts of the hair use a different shading model. For example, my understanding is the hair shading model is best suited to individual planes, perhaps they split parts of the hair into subsurface and some into hair.
or maybe they just decided that hair worked well enough for snow and just changed the Base color/roughness