If you're bewildered by the number of open cloud platforms and usage models for them that are available, there are some useful new guides you should know about. The Linux Foundation has announced the release of its 2015 report "Guide to the Open Cloud: Open Cloud Projects Profiled." To download the full report, you can visit The Linux Foundation's Publication's website at: https://www.linuxfoundation.org/publications/linux-foundation/guide-to-the-open-cloud
Meanwhile, The Open Data Center Alliance has issued a “usage model” that defines how computing, network and storage resources combine to form cloud infrastructure. It is available here.