Most Spa topside control panels can be identified in several ways. If you remove the topside, there should be a sticker with a part number and descriptive information. The part number can normally be searched to find the exact topside.
You can also use the overall shape, size, and buttons. A.k.a the general appearance. If it looks right, it probably is right. Rarely, a single topside will be made with different cords. Be sure to match the end plug style as well as the general appearance. If you make a match based on an exact part number, the plug should already be matched.