It's such a classic question, and the answer seems to depend on lot on who you ask. Growing up, my family always referred to potatoes layered and baked this way as scalloped potatoes. But my husband's family called them au gratin. According to Southern Living magazine, the difference comes down to whether you include cheese in the recipe and whether bread crumbs are placed on top. To add to the confusion, you'll find plenty of variations in many cookbooks and on restaurant menus. Truthfully, no matter what we call them both scalloped potatoes and au gratin potatoes are a comforting and delicious way to serve potatoes.