Flat warts and hives are two different diseases with significant differences. First, the causes of these diseases are different. Flat warts are caused by human papillomavirus infection, while hives are related to allergies, usually caused by exposure to an allergen, and the specific cause needs to be determined through testing, with many cases having an unknown cause. Secondly, their treatment methods are also different; flat warts are often treated with lasers, cryotherapy, antivirals, etc., while hives are commonly treated with anti-allergy methods.