Usage
Three-season tents are the most popular choice because they are ideal for spring, summer and fall. They can withstand moderate weather, such as light to moderate snow, rainfall, and winds. Four-season tents are best if you expect to endure strong winds or heavy snow during your camping trip.
Material
Three-season tents often have mesh panels for ventilation. Four-season tents, however, do not. No mesh panels means they insulate and keep in heat more easily. Four-season tents are also made of thicker, more durable fabric than three-season tents. The thicker fabric also means that four-season tents are generally heavier than their three-season counterparts.
Poles
Four-season tents generally come with more external poles that the three-season variety. In addition, these poles are wider and stronger, making them heavier. The poles on a four-season tent provide a stronger and more stable frame so the tent can withstand heavier rain, snow, and winds.
Design
Four-season tents often differ from three-season tents in their geometry, because they are designed with coping with wind and shedding snow in mind. They are made in bright colors so they are easy to find. Because of their stronger material and stronger poles, four-season generally cost more than three-season tents, though the overall price of three- and four-season tents depends on brand, size and other features.