We use this analogy on our web hosting page. Shared hosting is like an apartment building – lots of residents in the same building, sharing the same resources, but also very affordable. Dedicated servers are like having your state-of-the-art house, where you’ll pay a lot more, but you also don’t have to share the space or utilities with anyone. VPS is in the middle, like a townhouse, where you have a few residents in the same building, but you each have dedicated resources and are in full control of your home. It costs less than a dedicated server, but still gives you much of the same benefits.
A Content Distribution Network (CDN) is a network of servers distributed geographically. The purpose of a CDN is to deliver content on the internet much faster. If a user in Toronto is trying to access your website, the closest server to them will take care of this. But someone coming to your website from Sydney, Australia, will be catered to by a server closest to them. The main host server holds your website content, and all the other servers have a cached version each.