The type of products you are selling will determine the structure of your store. Different types of products will have different requirements in terms of the information presented to the customer, and the data that you will need to collect in order to fulfill an order.
Every product needs to have the following fields which are added by default:
This is the minimum you need to define a product in Drupal Commerce—everything else is customized for your store. You can define multiple Product Types (Product Entity Bundles), which can contain different fields depending on your requirements.