Website Builder offers two eCommerce solutions, native eCommerce and third party eCommerce. If you are in the platform and are unsure about which solution you are using you can check two places, the top of the Sell Online panel and the Store Management menu.
To check which solution you are using, in the side panel, click Sell Online. This opens the Sell Online panel. At the top it will be labeled either native eCommerce or third party eCommerce.
Native Store:
Third Party Store: