Charts can use metrics about services, applications, processes, or hosts. You select the data you want to see in what format is useful for you.
The reports are simplified summaries that will give you an idea of how your application performed over the last week. It is almost like an executive summary that would be good for people who don't need to drill into or build their own charts and dashboards.
Yes, they are based of the same data but charts let you pick exactly what you are seeing and they are for different use cases. A report for a high level look at performance vs charts and dashboards for lower level or more detailed looks for monitoring or analysis of an issue.
From that linked documentation:
"Reports are structured in such a way that even non-technical team members can understand them."
Have you had the chance to look into the generated reports and maybe make some custom charts to more easily see the difference?
