Ski mask and balaclava are basically interchangeable names for the same style garment. Both differentiate from what is referred to as Beanie or a Neck Warmer. The ski mask or balaclava completely covers the head, neck and most of the face, providing not just wind and cold weather protection but also flexible insulation, warmth as well as protection from debris, dust, sand and flying bugs! Beanies are similarly made from knitted wool or thermal fabric but designed like a skullcap to tightly fit the top of the head and be pulled down to keep the ears warm. Neck warmers differ again in that they are generally a tubular design, slipped over the head, covering the bottom half of the face and leaving the top exposed.