The "scan disc" test is a bit different from the "Disc Quality" test.
It consists of two tests:
1) File test: check file readability, and report all errors.
2) Surface scan. It examine disc surface to search damaged sectors. It report results in graphical way. Yellow sectors are damaged ones that can still read with the internal error correction routines of the drive, so data can still be retrieved.
Red sectors are damaged, and unreadable. They should be the same of POF showed in Disc Quality test.