Four season tents have stronger structures to resist wind and snow loads. They have limited mesh areas and are designed to protect against blowing snow. They are inferior to three season tents during most conditions due to increased weight and poor ventillation. In low temperatures, four season tents are susceptable to condensation. If you are camping in the winter, once your sleeping bag gets wet, it will stay wet until you dry it indoors. Unless you are winter mountaineering above tree line, you'd be better off with a three season tent even for a winter cross Canada ride. We tour on public roads and it's always easy to find a building to camp behind. For blowing snow, get a three season tent with a fly which reaches the ground, and shovel snow against the edge of the fly. Put your door and vestibule on the leeward side.
Four season tents offer no more protection against hail than three season tents.