Drillthrough, Drilldown, Subreports, and Nested Data Regions
You can organize data in a variety of ways to show the relationship of the general to the detailed. You can put all the data in the report, but set it to be hidden until a user clicks to reveal details; this is a drilldown action. You can display the data in a data region, such as a table or chart, which is nested inside another data region, such as a table or matrix. You can display the data in a subreport that is completely contained within a main report. Or, you can put the detail data in drillthrough reports, separate reports that are displayed when a user clicks a link.
A. Drillthrough report
C. Nested data regions
D. Drilldown action
All of these have commonalities, but they serve different purposes and have different features. Two of them, drillthrough reports and subreports, are actually separate reports. Nesting is a means of putting one data region inside another data region. Drilldown is an action you can apply to any report item to hide and show other report items. They all are ways that you can organize and display data to help your users understand your report better.