What are the two ways a siberians fur differs from summer to winter?

1) Thickness: A Siberian's fur thickness can double or even triple during the winter months, providing extra insulation and warmth.

2) Guard hairs: During winter, the guard hairs on a Siberian's coat become longer, thicker, and coarser to repel moisture and snow, while the dense undercoat becomes longer and softer for trapping heat.