This is a major difference between the DuoClean Speed and Rotator lift away, the DuoClean Speed has dual brushrolls – one bristle brushroll and one soft roller. While the Rotator has only bristle brush.
Lift Away Design
Though both of them have lift away design, the DuoClean Speed has Powered Lift Away function that allows you to use Powered tools including the motorized nozzle when in lift away mode, whereas the Rotator only allows you to use air driven tools.
Surface Selector vs Brush On/Off + Suction Control
The DuoClean Speed has surface selector that allows you to choose between Hard floor, Carpet&Low Pile, Thick Carpet&Area Rug. It has NO button to turn off the brushrolls, and no suction control. However, the brushroll speeds and suction power vary according to your surface setting.
Whereas the Rotator has Brushroll On/Off control as well as a separate suction control collar, so you can clean floors with suction only or suction with brushroll, and adjust the suction power to meet your cleaning needs such as vacuum delicate things with weak suction.
Dust Cup Size
The Rotator has larger dust cup which holds 1.3 dry quarts to the fill line versus 0.9 dry quarts on the DuoClean Speed.
The DuoClean Speed power specifications are 120v,60hz,1150w,9.5a versus 120v,60hz,1200w,10a on the Rotator.
The DuoClean Speed has a 7 year limited warranty versus 5 year limited warranty on the Rotator.
Learn more by reading manuals:
Rotator Lift Away NV500 Series Manual – http://www.sharkclean.com/include/pdf/manual-NV500.pdf
DuoClean Powered Lift Away NV800 Series Manual – https://www.sharkclean.com/include/pdf/manual-NV800.pdf