The colour denotes level of difficulty... In a very basic description;
1-White trails (Extreme or High experience level) are The Garnsey & the Extension, Woodys Wonderland with The Transect, Hells 1/2 Acre, M.L. Bypass
2- Pink level (High Intermediate) Newfie Autobahn, Oriole Lake
3-Orange for (General Intermediate) trails like Pitbull, Lost Saint, Missing Link, Toms Trail and Roddens Route for examples
4-Green (easy)...the Hydro lines and some of the connector ATV trails and dirt roads.