Regarding the Winter Level of Service maps, how does MDOT prioritize routes into Orange and Blue and what's the difference?

Orange routes represent the first priority for winter maintenance; Blue routes represent MDOT's second priority.

Orange routes are state trunklines of statewide, national or international significance, linking population and activity centers. Blue routes are state trunklines of local importance, feeding into the more heavily traveled routes.  These designations can be found within MDOT's Level of Service maps by region.