What is the meaning of emphasized and unemphasized Sunnahs?

Confirmed Sunnahs, according to some scholars, are applied to certain regular (supererogatory) prayers, which are ten rak'ahs: two rak'ahs before Dhuhr and two after it, two rak'ahs after Maghrib, two rak'ahs after Isha, and two rak'ahs before Fajr. The best of these is the Sunnah of Fajr, then the Sunnah of Maghrib, then the Sunnahs of Dhuhr and Isha. The confirmed Sunnah may also refer to what the Prophet, peace and blessings be upon him, consistently performed, such as the regular supererogatory prayers and Witr. As for the unconfirmed Sunnah, it is that which the Messenger of Allah, peace and blessings be upon him, did not consistently perform.