The second report format that we will now create is the Summary Report. Summary Reports are where you introduce groupings of your data by which you can then summarize that data.
A matrix report contains data that is grouped by row and column. In this lesson, we create a matrix report.
The joined report format lets you view different types of information in a single report. A joined report can contain data from multiple standard or custom report types. You can turn any existing report into a joined report using the report builder.
Resources:
Combine Different Types of Informat...
What happens when you change the format of a report? We address that question in this video lesson.
Resource:
Choose a Report Format - https://help.salesforce.com/articleView?id=reports_changing_format.htm&type=5