To begin with, let’s define what Cloud Computing actually is. Cloud Computing in the most basic of terms is the act of using the internet for your basic computing needs so that you can cut back on hardware and software used to run your company. With that said, SaaS and Cloud Computing are 100% interchangeable as SaaS is a part of Cloud Computing. Cloud Computing is a range of different things, this includes SaaS (for Software), HaaS (for Hardware), PaaS (for your Platform or OS), IaaS (for Infrastructure) and there are still others.
Cloud Computing also has three major deployment models External where everything is hosted at a separate provider, Hybrid which is both part hosted by the provider and part hosted in house, and Private where it is more of a emulation of a cloud environment in house.