The Miru Nuva was the more powerful version of the Mask of Levitation. It actually did allow a semblance of flight. With a proper head start, a user could rise into the air and remain aloft without the aid of updrafts.
The Great Mask of Levitation. It allowed the user and those close by to soar into the air and reach amazing heights.
The Kanohi Miru Nuva was the Great Mask of Levitation. It allowed its user to soar into the air and reach amazing heights.
While in Karda Nui, Lewa Nuva's Miru Nuva gave him the ability to maneuver better while in flight.