These two Shark upright vacuum models have similar things – detachable canister for portable cleaning, anti-Allergen Complete Seal Technology with HEPA filter, swivel nozzle, headlights. However, there are also some obvious differences.
Nv831,nv835 are newer models, belong to the DuoClean powered lift away series NV501 belongs to the Rotator lift away series.
The biggest difference between the DuoClean and Rotator is the brush bar design, the DuoClean has dual brush system – one bristle brush and one soft roller. While the Rotator has only one bristle brush.
Another big difference is that the DuoClean has Powered Lift Away function while the Rotator NV500 only has Lift Away mode. With Powered lift away, you can use the Powered tools such as motorized brush. Whereas the lift away feature only allows using air driven attachments.
Other difference between them:
Control Button Location.
The DuoClean NV831,NV835 has the Power Button on the handle whereas the Rotato has the power control on the top of the lift away canister.
And the DuoClean has the surface selector on the handle for fingertip control while the Rotator has the Brushroll on/off button on the top of the lift away pod, so you may have to bend down to turn on/off brushroll when switching between floors.
Floor Cleaning Modes
The DuoClean has 3 surface settings – Hard floor, Carpet&Low Pile, Thick Carpet&Area Rug, the brushrolls are always spinning no matter which setting you select, but the speed varies.
While the Rotator has a BRUSHROLL button that you can use to turn on or off the brushroll to meet different cleaning needs.
The Rotator has a suction control collar on the handle that allows you to release suction when you need weak suction to clean delicate things. While the DuoClean has no similar control.
Led lights on handle
The DuoClean has LED lights on the handle and nozzle whereas the Rotator has lights on the nozzle only.
The DuoClean power specifications are 120v,60hz,1150w,9.5a versus 120v,60hz,1200w,10a on the Rotator.
The DuoClean is backed by a 7 year limited warranty rather than 5 year warranty on the Rotator.
The DuoClean is a bit heavier than the Rotator.
The dimensions of DuoClean are 47.2″ x 12.20″ x 10.6″ versus 45.7″ x 13.4″ x 12.2″ on the Rotator.
Learn more by reading manuals:
Rotator Lift Away NV500 Serie Manual – http://www.sharkclean.com/include/pdf/manual-NV500.pdf
DuoClean Powered Lift Away NV830 Series Manual – https://www.sharkclean.com/include/pdf/manual-NV830.pdf
P.S. Shark Rotator NV500 series vacuum cleaners are similar items, DuoClean Powered Lift Away series models are also similar, you can read comparison here.