Snowboard gloves are generally made from fabric with leather or synthetic leather palms and reinforcements. Leather may require longer break-in and occasional treatment, but it's very durable and greater dexterity. Gloves with synthetic leather palms are usually less expensive, and are designed to withstand edge grabs.
Insulation in a snowboard glove offers much-needed warmth that'll keep you from hitting the lodge early. These gloves feature synthetic insulation (which, unlike down, keeps you warm even when it's wet); if your hands run cold, look for higher-weight padding. Some gloves have more insulation on the back than the palm, balancing warmth with dexterity.
During the winter, wetness is just as dangerous as the cold. Look for a glove with a waterproof breathable shell or internal membrane like Gore-Tex, eVent, Outdry, or a brand's proprietary technology, and compare waterproof ratings. At the very least, you'll need a glove with a waterproof coating.
The cuffs for snowboard gloves fall into two categories: gauntlet or undercuff. A gauntlet-style glove slips over the sleeve of your jacket and cinches to keep the elements out. This design can feel bulky to some, so if you want a sleeker fit look for an undercuff glove with a slim profile that slips under your jacket cuff.