Just as there are different types of clouds in nature such as the Stratus, Cumulus and Cirrus formations, there are different types of Cloud Computing offerings available. Sure they can all be identified generically as Cloud offerings, but they have different purposes; storage, computational or process focuses.
Even within each category of cloud computing offering, there are key attribute differences. Think of the recent volcanic laden clouds drifting from Iceland over Europe as compared to the same type of clouds sitting here in St Louis. The clouds might look physically the same, but the composition is completely different. Data processed and stored in the cloud is always physically located somewhere and that hardware has physical performance characteristics. Whether that be speed, redundancy, security attributes or indeed operator abilities and competency. Sure economics are one way to measure cloud offerings, but don’t forget about the other key attributes!!