Varicose veins and spider veins are common vein diseases. Varicose veins are bigger and more visible than spider veins. Varicose veins are larger, swollen, twisted veins and are commonly found on the legs. They often cause discomfort, pain and heaviness in the legs. Spider veins are smaller, thinner veins that are a blue, red or purple color. They are called spider veins because they look similar to spider webs. Spider veins are commonly found on the legs or face and for the most part are painless. The main reason people seek spider vein treatments is due to cosmetic reasons.