Difference between foodstuff and supermarket in Korean
식품·슈퍼마켓

식품foodstuff
식품 means foodstuff or food products. It is used for things people eat or drink, especially in stores, on packages, and in simple official situations. In daily life, it often means food items in general, not one cooked dish.

슈퍼마켓supermarket
슈퍼마켓 means “supermarket,” a large store that sells food, drinks, and household items. People use this word when talking about everyday shopping. You can hear it in sentences about buying groceries, going out with family, or stopping by a store after school or work.
The difference
식품 means food products or grocery items. It is the thing you buy, not the place you shop.