Ecommerce Hosting is a name of hosting plan just like business hosting, corporate hosting. Most of the web hosts named their hosting plans as Ecommerce Hosting plan that includes more space, bandwidth, ram etc. Actually these are required to run a Ecommerce sites and due to this hosting requirements to run a Ecommerce site called Ecommerce Hosting plan.
That is no different , mostly hosting able for you to host a email account, a blog , a website or a commerce site. Why they call it as ecommerce hosting is because the hosting is design specific to ecommerce user which may include all the software and plug in like shopping cart, ecommerce site builder, e-commerce site template, payment gateway and so on which is ready inside for you. It already customize down so it call as e-commerce hosting.