If you are deciding between Shark Apex Upright with DuoClean Zero-M Powered Lift Away AZ1000/AZ1000W/AZ1002 and DuoClean Powered Lift Away Speed UV810/NV800/NV800W/NV801/NV803, the comparison info below may help you make an informed decision.
(Shark DuoClean Powered Lift-Away Speed models comparison, Shark Apex DuoClean Zero-M Powered Lift Away models comparison)

images from Shark official site

• Zero-M Technology
  This is one of the main difference between between these two vacuum series.
  The AZ1000 series feature Zero-M self cleaning brushroll whereas the NV800 series/UV810 do not have this technology. According to Shark, this new design actively removes human and pet hair wrap from the brushroll while users vacuum.
  If you want to try the anti hair wrap feature, buy the AZ1000 series Apex DuoClean Zero-M Powered Lift Away.

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• Size
  This is another big difference between them. The AZ1000 series is a larger model while the NV800 series/UV810 is more compact. You can notice the difference from the weight,dustbin capacity, cleaning path width, and power specifications.
  The AZ1000 series weighs about 17 lbs which is over 2 lbs heavier than the NV800 series/UV810.
  The AZ1000 series has a dust cup that holds up to 1.5 dry quarts versus 0.9 dry quarts on the NV800 series/UV810.
  The AZ1000 series has a wider cleaning path width.
  The AZ1000 series power specifications are 120V,60Hz,1350W,11.3A whereas the NV800 series/UV810 power specifications are 120V,60Hz,1150W,9.5A.
  If you want a compact Shark vacuum for small house, buy the NV800 series/UV810; if you have larger house, then go for the AZ1000 series.
• On/Off Location
  The AZ1000 series On/Off switch is located on the handle for fingertip control whereas the NV800 series/UV810 power button is located at the top of the lift away pod. It is obvious that control on the handle is more convenient, because you do not need to bend.
• LED lights
  The NV800 series/UV810 has lights on the nozzle only while the AZ1000 series has lights on the nozzle and handle. Some people like the LED lights on the handle so much, because they think it helps cleaning dark areas when using the accessories, such as using the crevice tool to vacuum low light crevice.
• Brush Rolls Cleanup
  Both of them have 2 rollers – a bristle brush to clean carpets, and a soft roller to pull in particles and clean hard floors.
  The soft roller on both series can be removed to clean blockage.
  The bristle brush on the AZ1000 series cannot be lift up to remove string,hair,and other debris that wrap around, whereas the NV800 series/UV810 bristle brush can be detached to clean up.

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• Warranty
  The NV800W is backed by Shark’s Lifetime VIP warranty; NV800, NV800C, NV801, NV803, and UV810 carry a 7 year limited warranty; NV801Q carries 5 year limited warranty.
  While the AZ1000 series carry 5 year limited warranty.

Similarities and things you may want to know before buying:

• Surface Settings
  Both of them have 3 preset cleaning modes – Thick Carpet/Area Rug, Carpet/Low Pile, Hard Floor.
  You can just select between these three options, there’s no other pile height adjustment for carpet cleaning.
  When setting to Hard Floor mode, the brushrolls remain rotating at a slow speed. That means there is no suction only mode for hard floor, you cannot turn off the rollers when cleaning floors.
  And there is no other way to adjust the suction level except for the above 3 preset options.
• Powered Lift-Away
  Both of these vacuum cleaners feature powered lift away, which allows you to detach the vacuum pod from the vacuum cleaner, and still can use motorized tools with the wand and handle. This is a useful feature that makes cleaning underneath furniture a breeze. And also good for using powered tool to pull up pet hair from upholstered surface.
• Anti-Allergen Complete Seal Technology plus a HEPA filter
  These two things trap dust and allergens inside the vacuum, and emit clean air. For anyone who suffer from asthma and allergy, this is a plus.
• Both features swivel steering.
• Both are bagless, use dust cup to collect debris.
• Filters are washable.
• Both have the surface selector located on the handle for easy switching between hard floors and carpets.

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For more intuitive comparison, read the table below: