As noted earlier, the choice of data structure is very much up to you. You do not have to make the product Form match a particular structure, but you simply identify to the ecommerce system which fields are to be used for specific purposes.
For example, you need to identify which field contains the product Name, and the Price, and if you are using stock control, which field contains the quantity in stock.
The product Form does not have to be a single Form, but can be a Query based on several Forms. This is useful if some information will always be the same, and you do not want to enter it for every single record.