With IaaS the IT department have the most flexibility and management control over resources as
only the infrastructure layer is provided by the Cloud Provider. Everything else is managed by
the end customer. This means more control and more responsibility for management.
With PaaS and SaaS, the Cloud Provider manages up to a higher level in the stack. This means that
as an organization using the service you have less control (and less responsibility).
On-premises cloud is a cloud deployment model, not a cloud computing model. Other cloud
deployment models are Private, Public and Hybrid.