What makes outdoor extension cords different from indoor ones besides the jacket?

Outdoor cords use heavier gauge wire to prevent voltage drop over long distances, have molded or sealed plugs for moisture protection, and are almost always grounded. Indoor cords often use smaller wire, lack grounding, and have no moisture protection. The jacket material also differs — outdoor cords use rubber or heavy vinyl that stays flexible and resists UV, while indoor PVC gets brittle in cold. Using an indoor cord outside is a short circuit risk.