The terms are often used interchangeably, but they technically represent different things. "Dumpling" is an umbrella term that describes a small ball of dough that can be filled or unfilled. Gyoza are a type of dumpling made by filling a round wrapper with a vegetable and meat filling. These can be cooked in various ways, such as boiling, deep-frying, or pan-frying. "Potstickers" refers to Gyoza that have been pan-fried (then tend to stick to pans without a non-stick coating).