Product options are properties, such as size, color, and style.
Variations are the attributes of the properties. For example, if you were using the product option Size, your variants would be small, medium, large, etc.
Marketplaces limit the number of product options and variations that can be added to products. When a vendor has more than that max amount, they will use a third-party app.
It is important to note that when a vendor uses a third-party app, Onport cannot translate those options/variations into your Marketplace store. They will appear as only a single product in your Onport account (No variations or options).
If you are seeing only one product but you know there are variations of the product, contact your vendor to find out if they are using a third-party app.
As a workaround, you can add a third-party app to your Marketplace account as well, and have the vendor send you a spreadsheet of the products for creating in your Shopify store using the app.