Amazon supports a limited amount of variants within some categories, such as sizes and colors for apparel. If your items belong in one of these categories you should be listing them as variants. This means your products on Amazon are all children of a generic parent item. People buying on Amazon will be able to select which variant they want from a drop-down. You can also create product variants in Brightpearl, so you can link them all up and ensure all the quantities and prices update correctly.
When connecting these items to products in Brightpearl each one will download as an individual listing and so will need to be connected to the relevant variant in Brightpearl (the parent is not downloaded or connected). It remains a one-listing-to-one-product connection and works in the same way any individual listing would.
Variants cannot be created from Amazon listings. If the listing is used to create the product the options will simply be in the product name. It is better to add the product range with all the variants from within Brightpearl and then to connect them to the listings using SKUs.
Variants synchronize as normal since they are a single product-to-listing connection.