Let’s learn the difference between Shark Rocket Pro Cordless Stick Vacuum IZ140, IZ140C, IZ142 and UZ145 below:

• Headlights
  The IZ140 and IZ140C have no headlights whereas the IZ142 and UZ145 equipped with LED headlights on the nozzle.
• Accessories
  The IZ140 comes with a MultiFLEX Wand, a Dusting Brush and an 8-inch Crevice Tool.

  The IZ140C comes with a Straight Wand, an Upholstery Tool and an 8-inch Crevice Tool.

  The IZ142 may come with a Straight Wand or a MultiFLEX Wand, a Pet Multi-Tool and an 8-inch Crevice Tool.

  The UZ145 may come with a Straight Wand or MultiFLEX Wand, a Dusting Brush and an 8-inch Crevice Tool.

• Color
  The IZ140 is Teal, the IZ140C is Green, whereas the IZ142 and UZ145 are Orange.

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Similarities:

• Can be used as a stick vacuum or transformed into a handheld vacuum to tackle different cleaning jobs.
• Cordless, powered by 1900mAh 21.6V Lithium-ion rechargeable battery (battery part number XFBT620). Battery can only be charged in the vacuum.
• Self-cleaning brushroll for removing hair without hair wrap.
• PowerFins provide non stop contact to clean carpets and floors.
• Carry 5-year limited warranty on the unit, 2-year limited warranty on the battery.
• Washable filters. It is recommended to rinse them with water only, clean the 2 pre-motor filters at least once a month and post-motor filter at least once a year.
• Bagless, transparent dust cup holds 0.34 dry quarts.

Some questions and answers:

• Do they have a wall mount?
  No.
• Is the battery removable?
  The battery is fixed, it is replaceable but requires tools to replace. Not the type that you can get a second battery to easliy swap out to extend the running time.
• How long will it take to charge?
  A full charge takes approximately 3 – 3.5 hours.
• What’s the run time?
  Depends on which mode and setting you choose.
  They have Standard mode and Boost mode, Bare Floor setting and Carpet setting.
  When using as a hand vac, they run up to 40 minutes in Standard mode, up to 10 minutes in Boost mode.
  While using with the floor nozzle, choosing Bare Floor setting, they run up to 25 minutes in Standard mode, up to 10 minutes in Boost mode.
  While using with floor nozzle, choosing Carpet setting, they run up to 20 minutes in Standard mode, up to 10 minutes in Boost mode.
• Do you have to continuously hold a button to use them?
  They have On/Off control, in standard mode, you do not have to keep pressing the button. However, if you need more suction power, you will need to pull the Trigger
  on the handheld vacuum to enter the Boost mode for extra power. And release it to return to standard mode.

The Shark HZ2002 and HZ251 corded stick vacuum cleaners look similar. If you are deciding between them, we will help you make an informed purchase.
Below is the main difference between Shark HZ2002 Vertex Ultralight DuoClean PowerFins Corded Stick Vacuum and Shark HZ251 UltraLight Corded Stick Vacuum:

Vacuum	Shark Vertex Ultralight DuoClean Powerfins Corded Vacuum HZ2002	Shark Ultralight Corded Stick Vacuum HZ251
Model	HZ2002	HZ251
Design	Stick & Handheld 2-in-1	Stick & Handheld 2-in-1
On/Off Button	Yes	Yes
Power Source	Corded	Corded
Amps	5.7	5.7
Wattage	680	680
Cord Length	30-foot	25-foot
Speeds	2	2
LED Display	Yes	No
DuoClean Technology	Yes	No
Self Clean Brushroll	Yes	Yes
PowerFins	Yes	No
Brush On/Off	No	No
Headlights	Yes on the nozzle	Yes on the nozzle
Dust Collection Type	Bagless	Bagless
Bin Capacity	0.32 quarts	0.32 quarts
Anti-Allergen Complete Seal System	No	No
HEPA Filter	No	No
Washable Filters	Yes	Yes
Cleaning Path Width (inch)	8.11	8.71
Wand	Yes	Yes
Hose	No	No
Accessories	(1) Dusting Brush (1) Crevice Tool (1) Self-cleaning Pet Power Brush (1) Onboard Storage Clip	(1) Anti-Allergen Brush (1) Upholstery Tool (1) Pet Crevice Tool (1) Onboard Storage Clip
Weight	9.05 lbs	8.31 lbs
Dimensions (inch)	10.24" X 10.24" X 45.27" (L x W x H)	10.24" X 10.24" X 45.27" (L x W x H)
Warranty	5 year limited warranty	5 year limited warranty

• Floor Nozzle
  The HZ2002 has a DuoClean PowerFins floor nozzle with self cleaning brushroll whereas the HZ251 has a one roller floor nozzle with self cleaning feature.
  The DuoClean PowerFins floor nozzle has two rollers: a soft roller to pull in large particles and fine dust for a polished look on hard floors, and a roller with flexible silicone fins to deliver non stop contact on carpets and floors, result in more dirt collection in every pass.
  Shark claimed that the self-cleaning brushroll will pick up hair without wrapping problems.
• Cord Length
  The HZ2002 has a cord length of 30-foot whereas the HZ251 has a 25-foot cord.
• Control
  The HZ2002 has a floor selector button that allows you to press to toggle between Bare Floor and Carpet settings. Whereas the HZ251 uses a slider to get things done.
• LED User Interface
  The HZ2002 has LED Display that makes it intuitive when changing cleaning modes. While the HZ251 does not has the LED display.
• Accessories
  HZ251 comes with a Pet Crevice Tool, Upholstery Tool, and an Anti-Allergen Dusting Brush, Onboard Storage Clip.
  HZ2002 comes with a Dusting Brush, Crevice Tool, Self-cleaning Pet Power Brush, Onboard Storage Clip.

  Pet Crevice Tool is a 8-inch tool designed for removing pet hair from corners, baseboard, and other hard-to-reach spaces.

  Upholstery Tool can be used to remove pet hair, dust, and large debris from delicate upholstered fabrics.

  Anti-Allergen Dusting Brush has nylon fiber bristles designed for removing cleaning the most delicate surfaces.

  Dusting Brush dusts and cleans delicate surfaces such as lampshades.

  Crevice Tool is for cleaning in tight places and hard-to-reach areas.

  Self-cleaning Pet Power Brush actively removes hair wrap as it cleans upholstery and carpeted surfaces.

  Onboard Storage Clip can be snapped onto the wand to store up to two accessories.

• Weight
  The HZ2002 weighs 9.05 lbs versus 8.31 lbs on the HZ251.
• Cleaning Path Width
  The HZ2002 has a cleaning path width of 8.11-inch versus 8.71-inch on the HZ251.

Similarities:

• Corded.
• 2-in-1 design: can be used as a handheld or a stick vacuum.
• Featured self-cleaning brushroll.
• Bagless, have a dust cup holds up to 0.32 dry quarts.
• Both have two floor settings.
• Have washable foam and felt filters.
• Removable dust cup for emptying.
• Hand unit can be hooked onto the wand for storage.
• Carry 5-year limited warranty.

Questions and answers:

• Do they have On/Off control or do you have to keep pressing the trigger?
  They have On/Off power button. You don’t have to keep holding down the button.
• Do they stand upright by their own?
  No. When not in use it will need to be leaned against something or the hand unit need to be stored on the hook on the wand.
• Do they have headlights?
  Yes, there are headlights on the nozzle. But no lights on the hand unit.
• Do they have HEAP filter?
  No.
• Are the filters washable?
  Yes.
• Do they have a wall mount?
  No.
• Can the rollers be turned off when cleaning delicate surfaces?
  No. In Bare Floor setting, the roller still spins, but at a slow speed.

The main difference between the Shark Vertex DuoClean Powerfins cordless stick vacuum IZ440H and IZ462H is the battery.

• The IZ440H has a built-in battery which is not removable. To charge the battery, you have to plug the charger directly into the port on the hand held unit.
  While the IZ462H has a detachable battery which can be charged on or off the vacuum cleaner.
  According to Shark, the IZ440H runs up to 50 minutes when using as a hand vacuum whereas the IZ462H runs up to 60 minutes.
• Accessories
  The IZ440H comes with a Dusting Brush and a Crevice Tool whereas the IZ462H comes with an Anti-Allergen Brush, a Pet Multi-Tool, and a Crevice Tool.
  
  

  images from shark clean.com

  Dusting Brush
  The dusting brush allows you to adjust the angle of the brush head to clean surface like baseboards, countertop, shelves, etc.

  Crevice Tool
  The 8-inch crevice tool can be used to help clean nook and cranny, high and low areas.

  Anti-Allergen Brush
  This anti-allergen brush is designed specifically for removing fine dust and allergen particles from delicate surfaces.

  Pet Multi-Tool
  The 2-in-1 tool can be used to remove stubborn debris and pet hair, it has bristle brush part which is removable, you can use it as an upholstery tool with the brush detached, or use it as a brush tool with the brush attached.

• Color
  The IZ440H is in purple whereas the IZ462H is blue.

Vacuum	Shark Vertex DuoClean Powerfins Cordless Vacuum IZ440H	Shark Vertex DuoClean Powerfins Cordless Vacuum IZ462H
Model	IZ440H	IZ462H
Design	Stick & Handheld 2-in-1	Stick & Handheld 2-in-1
Power Source	Battery Powered	Battery Powered
Battery	Built-in Lithium-ion Battery	Removable Lithium-ion Battery
Charge Time	approximately 3 hours	approximately 3 hours
Run Time	Up to 50 minutes	Up to 60 minutes
DuoClean Technology	Yes	Yes
Self Clean Brushroll	Yes	Yes
Led Headlights	Yes	Yes
Dust Collection Type	Bagless	Bagless
Bin Capacity	0.34 quarts	0.34 quarts
Anti-Allergen Complete Seal System	Yes	Yes
HEPA Filter	Yes	Yes
Cleaning Path Width (inch)	10.63	10.63
MultiFLEX Wand	Yes	Yes
Accessories	(1) Dusting Brush (1) Crevice Tool	(1) Anti-Allergen Brush (1) Pet Multi-Tool (1) Crevice Tool
Color	Purple	Blue
Weight	9.04 lbs	9.04 lbs
Dimensions (inch)	10.24 x 9.65 x 46.46 (L x W x H)	10.24 x 9.65 x 46.46 (L x W x H)
Warranty	5 year limited warranty	5 year limited warranty

Otherwise, they are very similar:

• 2-in-1 Design
  Can be used as a stick vacuum, or transformed into a handheld vacuum.
• DuoClean with Powerfins
  The DuoClean includes two rollers in the vacuum floor head: a Soft Roller to pull in large and fine particles, and gives a polished look to hard floors; a PowerFins roller for cleaning carpets and floors with no gap.
• Self-cleaning brushroll which is claimed to tackle long & short hair with no hair wrap issues.
• Anti-Allergen Complete Seal system with HEPA filter captures and traps over 99.9% of dust, dirt & allergens.
• HyperVelocity accelerated suction power.
• Low-profile floor nozzle for getting under furniture.
• LED headlights
  LED lights on the floor nozzle to illuminate low light areas and reveal hidden debris to help you do a more thorough cleaning.
• The handheld unit can be used without any accessories due to its tapered design and the rubberized nozzle.
• MultiFLEX Wand
  The MultiFLEX wand flexes down for flexible reach and flex over for self standing compact storage.
• LED user interface for easy mode change.
• Easy empty dust cup.
• With the wand and crevice tool, they can be used to clean those hard to reach places including high and low areas.
• Carry 5-year limited warranty.

Download manual to learn more:
https://m.sharkclean.com/include/pdf/manual-iz462h.pdf