I generally divide cloud offerings first into two kinds, the commandline cloud (including IaaS and PaaS) and the SaaS cloud. There are of course also hybrid offerings which include both commandline and SaaS components. One example of commandline cloud would be Heroku, and for SaaS cloud would be Salesforce. Though in fairness Salesforce would also include hybrid elements. I define these hybrid clouds as ones that allow you to get under the hood and tweak the code. The SaaS cloud is not necessarily visual, as in GUI; I believe systems offering APIs to also be part of the SaaS cloud and hybrid SaaS cloud.