There are SAAS vendors (RackSpace Salesforce etc.), Cloud Vendors (Amazon, Microsoft , Google etc). So, what is the difference between the services offered? XaaS, where X is some kind of service, describes a specific Service Model of Cloud Computing. Therefore, an XaaS designates the nature of the service delivered to a client. There are lots of arconyms describing such models, however a vast majority of sources focus on the following three:
- Software as a Service (SaaS)
- Platform as a Service (Paas)
- Infrastructure as a Service (IaaS)
You can also meet the term Hardware as a Service (Haas) which is closely related to #3. The obvious difference between SaaS and the rest, is that SaaS delivers software, and not a platform (for software development) or infrastructure.