a few implementation details that you most probably don't care about (qStableSort uses qLess iirc, std::stable_sort obviously doesn't). In general, std::stable_sort will be a lot faster.

generally speaking: ou should prefer using STL algorithms over the ones in QtAlgorithms unless there is no direct replacement (qDeleteAll for instance) or unless your code somehow relies on the Qt algorithms (qLess being an example). There is upcoming changes in Qt to mark these all as deprecated to help give you a hint in the right direction, too.