All the features I've detailed to this point are valuable to the web hosting experience, but none matches the critical importance of site uptime. If your site is down, clients or customers will be unable to find you or access your products or services. It doesn't matter how great the features are, or how good it looks; if your site is down, it might as well not exist.
Similarly, in a real dedicated server, you will pay for the entire server that is not shared with anyone else. You will get complete control over all services. Unfortunately, it is also the most expensive hosting option and needs some technical expertise to manage. It is commonly used by those who have websites with specific scenarios, most commonly extremely high traffic and tight security requirements.
A VPS runs its own copy of an operating system (OS), and customers may have superuser-level access to that operating system instance, so they can install almost any software that runs on that OS. For many purposes they are functionally equivalent to a dedicated physical server, and being software-defined, are able to be much more easily created and configured. They are priced much lower than an equivalent physical server. However, as they share the underlying physical hardware with other VPSes, performance may be lower, depending on the workload of any other executing virtual machines.