Ya'll
Muffins can be sweet or savory.
Sweet muffins may have a topping like cinnamon sugar or some type of granulated sugar mixture sprinkled on top before baking. They may have dried berries, chocolate chips, etc in the batter before baking.
Savory muffins like cornbread muffins usually do not have a topping.
Cupcakes are sweet. They occasionally have chocolate chips or something similar mixed in the batter. They are always iced with a frosting usually made of powdered sugar and butter/margarine with some type of flavoring added in.