How compatible is Eucalyptus with Amazon's EC2!!!!!!!!!!!!

Eucalyptus is a private cloud-computing platform that implements the Amazon specification for EC2, S3, and EBS. Eucalyptus conforms to both the syntax and the semantic definition of the Amazon API and tool suite, with few exceptions. Along with providing a REST and SOAP interface compatible with Amazon AWS, Eucalyptus also exposes administrative functionalities (e.g., user management, storage configuration, network management, hypervisor configuration, etc.) for managing and maintaining the cloud. Eucalyptus implementation of the specification, however, is undoubtedly different than Amazon's implementations. These differences are related to several engineering design decisions. Eucalyptus primary goal is to provide an open-source software tool for community distribution that is highly scalable and extensible, as well as easy to install and maintain.