Your Site is where you host content all relating to the same brand or identity. Within your Site lives your Product(s), Store, Static Pages, and basically everything else you can think of! Assuming your Products are all under your same brand, you would want to keep them all under the same Site. Users have a single login for each site, so if your site has multiple products, they can access all purchased products under the same login. This makes upselling additional courses a very smooth process!