Seller Central products’ matching is performed through the field called SKU by Amazon, a value that the seller can freely associate to each product to identify them internally.
AmazonSync lets you select among three different sources for the SKU field: reference, EAN or supplier reference. This selection can be performed within the General tab. If products already on Amazon use one of these three Prestashop fields as SKU, then sending data from the website will update those available on Amazon. On the contrary, a new offer will be created on Seller Central.
It is possible to remove not matching codes (SKUs currently available on Amazon but that are missing on the website) enabling the Purge & Replace option (again within the General tab). WARNING: this operation will remove from Seller Centrall all the codes non present within the file generated by the module, FBA products included.