These transactions are recorded in the general journal first, and typically include more information than is included in the accounting ledger; the balance of each account is not included. As in the accounting ledger, however, the credits and debits listed in the general journal must total zero.
Grid Computing is a form of distributed system with non-interactive workloads. Utility Computing is a business model where computing resources are metered. Cloud Computing is a form of utility computing that allows developers to develop, deploy and run applications.
That's primarily the difference: SaaS offerings are applications that are fully formed end-user applications. Cloud Computing is computing infrastructure and services that you can rent. If you are in business, you will want to focus more on SaaS than cloud computing, unless your company develops software for a living.