In regards to hosting, cloud architecture refers to using an independent server for each aspect of the hosting service. Such a configuration leads to better performance since one machine will be used just for file storage, another one just for running databases, etcetera, which means that different system processes will not run on the exact same machine. The latter will minimize the chance of system errors significantly and will allow your websites to work faster, not mentioning the greater uptime. When you're looking for such a service, you need to double check that you'll really find it because a lot of companies advertise cloud web hosting plans, yet the control panels they use are not designed to function in a genuine cloud and can work only on a single server. The issue with using a single machine is that in the event that one service crashes or generates high load, the whole server will most likely go offline, so your sites will no longer be accessible.