Iscander_Che

QStringList list1;
    list1 << "Project1" << "NewProject" << "Project2";
    QStringList list2;
    list2 << "Project1" << "Project2";

    std::sort(list1.begin(), list1.end());
    std::sort(list2.begin(), list2.end());

    qDebug() << list1;
    qDebug() << list2;

    QStringList result;

    std::set_difference(list1.begin(), list1.end(), list2.begin(), list2.end(), std::inserter(result, result.begin()));

    qDebug() << result;