The major difference between the Shark DuoClean Powered Lift Away NV830 series and DuoClean Powered Lift Away Speed NV800 series is the size. The NV830 series are full size whereas the NV800 series are compact size. The full size has larger dust cup which holds up to 1.5 dry quarts versus 0.9 dry quarts on the compact size. And the full size has wider cleaning path and are over 2 pounds heavier.
Other differences between them are the headlights and power switch location.
The NV830 series have lights on the nozzle and handle, the lights on the handle are useful when vacuuming weak light spots with the attachments for above floor cleaning.
Power Control Location
The DuoClean Speed has the power control on the top of the lift away canister while the DuoClean has the power switch on the handle for finger tip control.
Otherwise, they are similar. Both of them feature powered lift away, DuoClean technology – a bristle brushroll to clean carpets, and a soft brushroll to pull in larger particles and directly engage floors, swivel steering, Anti-Allergen Complete Seal Technology, HEPA filter, 1150 watts and 9.5 amperage.
Shark DuoClean Powered Lift-Away Speed models comparison
NV800 series manual – https://www.sharkclean.com/include/pdf/manual-NV800.pdf
Shark DuoClean Powered Lift-Away NV830 models comparison
NV830 series manual – https://www.sharkclean.com/include/pdf/manual-NV830.pdf