In general, the size and shape of the 13 Pro Max and 14 Pro Max are slightly different, so their protective shells are not universal. While both have the same screen size (6.7 inches), the 14 Pro Max has a larger camera module, and it also has slightly different edges and bottoms than the 13 Pro Max. Therefore, if you use the protective case of the 13 Pro Max, you may not be able to fully cover the camera and edges of the 14 Pro Max to provide adequate protection. Therefore, it is recommended that you purchase a protective case designed for the 14 Pro Max to ensure that the phone is better protected.