Jira Server/Data Center applications are built on a different framework than Cloud applications.
What this means for R4J Cloud:
There is a gap in application maturity because Cloud development is young and still ongoing. Features in R4J Server/Data Center version may or may not be implemented in the Cloud version depending on customer feedback. We'll try our best to rollout the most important features you need first.
There are differences in data structure, infrastructure, and interface design. In R4J Cloud, we are given a clean slate to make different decisions to help with stability and usability which will improve you user experience in the long run.