Oracle BIEE includes 2 parts:
1. Oracle BIEE tools (stand-alone),2. Oracle BIEE applicaitions (a Oracle Build-in solution)
so, Oracle BI developer(Report) is asking for the persons who can use the Oracle BIEE tools.
But Oracle App developer(Report) means you need not only know how to use the BIEE tools, but also the how to use the build-in solution to build a report. It includes meta-data and flow.