eCommerce is the activity of digitally purchasing or selling a product. It can be through a website, social media or any third-party platform that allows an electronic transaction to happen.
Shipped manually by you, from your inventory or supply room, to your customers address
cloud based selling
The customer gets your product digitally, which means they can download or receive a pass to gain access to your product. Examples of this are Courses, eBooks, Software & Digital Tickets
Your supplier has the inventory and ships the order to the customer. However, you'll still need to forward each placed order and provide customer service (This is a widely popular way of selling, as there's very little investment needed)