Not too much for say, as there is no such thing as a true cloud web hosting platform. By looking up the definition of the cloud, you will see this. Some companies however, like Rackspace do offer a true cloud based hosting solution, however traditionally there is no real advantage to this in fact it can be negative under some circumstances.
Most providers that advertise that they offer cloud web hosting are only utilizing a platform such as CloudLinux, which is not cloud at all, it only offers the capability of being able to oversell solutions 10 times over. Others, rather than purchasing dedicated hardware for their customers will purchase a Cloud VPS and throw cPanel on it, claiming to be offering Cloud Hosting. However, this type of solution is not recommended as not only are you in a shared environment within the VM, but the VM itself is also within a shared environment. Not saying that a shared environment is bad, however running a hosting business off of a VPS would not be recommended as the provider would not be able to reach it's full potential under the heavy restrictions that a VM provides.
In the end, there are a lot of key things to look at when selecting a hosting provider. You will see hundreds out there that advertise they are in the cloud, however they only use the word as a marketing ploy as a lot of customers are misinformed about what the cloud is and what it does.