This explains the Report Designer interfaces in SI 2015.
There are three Report Designers in SI 2015. The Standard Report Designer is for creating custom Reports based off of the Reports that display under your Reports tab in the Project Explorer and the Project Editor:
The Order Report Designer is for creating custom reports for use on Tasks, Work Orders, and Service Orders:
You can also access the Report Designers in Create section of the ribbon in the Report Explorer:
SI 2015 Reports are designed in ActiveReports by GrapeCity. We use version 7 of ActiveReports.
From the Report Explorer you can also choose to create Excel reports using a wizard. Click here for details.