There are two types of e-commerce software; software as a Service (SaaS) which is hosted on the cloud and subscribed to, and On-Premise software, which is installed in your server.
SaaS is the most popular option as it is inexpensive, convenient, scalable and easy to use. With SaaS platforms like Shopify Plus, BigCommerce, and 3dCart, you pay your subscription, and in less than twenty minutes, you can have your shop up and running.
Moreover, you need not worry about software updates, as the e-commerce platform provider handles those and deploys them centrally. Your subscription cost caters for upgrades, maintenance, and customer service. However, this software offers you limited functionality; you cannot fully customize your site and only use pre-designed themes and plugins.
On-premise software like Magento and OroCommerce are often robust options that allow you to design your B2B online store from scratch. You can customize your website any way you wish, but these options are quite complex. You would need to have extensive tech expertise to install, configure and customize your website with these platforms.