Praise be to Allaah.
majority of scholars of Usool al-Fiqh say that there is no difference
between Sunnah, mustahabb, tatawwu’ (voluntary actions) and nafil. But
the Hanafis say something different. They regard mandoob (recommended)
as being of the same status as nafil, and they differentiate between
Sunnah and nafil, regarding Sunnah as being higher in status.