  Cloud computing is a new technology widely studied in recent years. Now there
are many cloud platforms both in industry and in academic circle. How to
understand and use these platforms is a big issue. A detailed comparison has
been presented in this paper focused on the aspects such as the architecture,
characteristics, application and so on. To know the differences between open
source and close source in cloud environment we mention some examples for
Software-as-a-Service, Platform-as-a-Service, and Infrastructure-as-a-Service.
We made comparison between them. Before conclusion we demonstrate some
convergences and differences between open and closed platform, but we realized
open source should be the best option.
