Ecommerce website is a term for any website that sales products or services online.
Ecommerce websites have online shops which display products and features to attract visitors/online buyers to shop online. Business sell products through the online shops, accept payments through various payment gateways available online. You can also have the eCommerce websites build responsive which enables your customers to buy your products and services online.
With eCommerce websites you no longer have to pay for edits. You get your own username and password for the content management system. through which you can edit content add new content images etc.
ECommerce websites have really good response on search engines. You can use various tricks and tools available in WordPress development to rank your website well on search engines.