You may want to get more specific. Land use depends on who owns it and it's intended use. Winter use of any motorized vehicle is prefered by most DNRs as the most desirable because their use does not leave ruts or damage vegetation.
In general, snowmobile Routes, are not trails, but are OK'd for snowmobile trafic. Snowmobile Trails were designed as primarily for snowmobile trafic, but are often designated for another use off season. The reason for closing a snowmobile Trail to non-snowmobile trafic is because tires mess up the snow base.