Cloud has become a broad term used to describe various products and services, which is supposed to be utilizing the distributed computing model. Strictly speaking “Cloud Server” is just a virtualized computer instance, a Virtual Private Server. However the term “Cloud” should mean that a “Cloud Server” is a computing instance created on top of an IT infrastructure in which the processing power (processing nodes) – CPU and RAM for example – reside on different physical machines than the data storage (SAN or storage nodes).
Some companies define “Cloud Server” for example as “on-demand virtual machine, created to deliver customizable performance and reliability”, although this is pretty much marketeer’s language. Please also be advised that billing a any virtual server hosting service (whatever it is labeled) on per minutes, per hour or per day basis doesn’t make it “Cloud”. What makes it a “Cloud Server” is the ability to scale up the allocated computing resources on demand.
To understand term “Cloud Hosting”, please read article “What does a Cloud Hosting Mean?“