Graphic Static reports are Procedure objects whose output is graphic (not text).
By default, the layout of any report is graphic, if not, you can change it by right clicking on the layout and selecting "Convert to Graphic mode".
PDF Reports are a particular case of graphic reports. Using the Report Viewer you can also implement graphic reports.
The Graphic report output property is used to determine the manner in which the reports of the model will be generated (only Java).