What's the main difference between a "potion" and a "medicine?"

Native speaker’s answer
Rebecca
A "potion" (countable) is a liquid with some expected effect on the person who drinks it. The word is almost always used to describe fictional or fantastical liquids that can do things like make people invisible or live forever. "Medicine" (uncountable) is a substance that helps someone heal from an injury or illness. The word is primarily used to describe substances with proven effects that will actually happen, such as helping to heal a wound. Ex: The witch made a potion that lets her fly like a bird. Ex: The doctor gave me medicine to help me stop coughing.