Cakes are soft and generally need eggs, flour, water and oil, such as Qifeng cake, which is the cake embryo in our common birthday cake. Some are made of cream cheese, such as cheesecake. The cake is baked at a high temperature in the oven. Mu Si is a dessert that does not need an oven during processing. Generally, just use refrigerator ice, don't heat it. This is their biggest difference.
Pies usually have sandwiches or fillings, just like you said apple pie and walnut pie. Cookies are soft butter cookies, so you must use butter when making them.