Hives or Urticaria is an outbreak of pale red plaques that appear on the skin causing itching or burn, whether in response to certain allergens or without a known reason. This is a reaction of the body to the histamine released from cells due to blood plasma leaks out of vessels in the skin. These plaques can appear anywhere on the body and sizes can go from a little bug bite to cover all the back surface, since they join together to form big plaques. They can last for a couple hours or for a few days.
Angioedema is similar to hives, but is characterized by deep swelling around the eyes, lips, genitals, hands, and feet. Swelling is deeper than in hives. It usually lasts longer than hives, but swelling disappears in less than 24 hours.
Rarely, angioedema occurs on the throat, tongue, or lungs, causing difficulty breathing.