I don't know what data is recorded on 777 QAR, but on our a bit older aircraft type where QAR was installed only through post-production SBs, QAR is basically recording 100% same data what is recorded on FDR. In fact both FDR and QAR are connected in parallel to the same data supply bus.
May be on a newer types where QAR is a standard equipment installed on production line, there are more options on what data you can record.