Here is some difference between Kenmore 31140, BU1005, Elite 31150, BU1017, Elite BU1018 Pet Friendly Bagged Upright Vacuum Cleaners:

(The 31140 and BU1005 are similar only with different colors, the Elite 31150, BU1017 and BU1018 are similar only with different colors.
So we will only discuss the difference between 31140 and Elite 31150 below.)

images from Kenmore.com

• Belt vs Beltless
  The 31140 use a belt to help drive the brush whereas the Elite 31150 is a direct-drive vacuum, its motor drives the brush directly without a belt. Since it has no belts to break, the beltless design cuts down on maintenance and repairs.
• Number of Motors
  The 31140 has 2 motors while the 31150 has a 3-motor system.
  The 31140 uses a conventional Kenmore upright vacuum motor, while the 31150 equipped with a 3D Inducer Motor that provides 20 percent more suction power than the conventional Kenmore upright vacuum motor.
• Dirt Sensor
  The 31150 features an infrared Dirt Sensor which activates a LED light when it detects dirt to help you do a more thorough cleaning, the light turns off when the floor is clean. While the 31140 has no such sensor.
• Carpet Pile Adjustment
  The 31140 has 4 settings while the 31150 has 5 settings.
• Cord Length
  The 31140 a 30-foot power cord while the 31150 has a 35-foot cord.

Similarities:

• Corded with manual wrap.
• HEPA filtration captures 99.97% of debris, dust, dander, pollen and other allergens, and emit clean air which is good for your health.
• Power Flow design helps maintain the suction power.
• Brush On/Off control and carpet height adjustment dial allows you to select the best settings to fit your cleaning needs.
• Headlights to help clean dark spots.
  The 31140 has the headlights above the nozzle whereas the 31150 has the lights at the front of them nozzle.
• Telescopic wand length is adjustable, helps you reach high and low areas, and other hard to reach spots.
• Check bag indicator to tell you when to change the bag or check possible clogs.
• Onboard tool storage for quick tool reach and neat storage. All the included accessories can be stored on the unit.

  The Combination Brush can be used without the brush for cleaning furniture,cushions,stairs or other surfaces that need greater suction power; while attaching the brush, it can be used for cleaning loose surfaces such as drapes.

  The Pet HandiMate is an air driven tool to help remove pet hair and other debris from furniture,stairs,car seats,etc.

  The Crevice Tool can be used for cleaning nook and cranny.

• The suction control located at one end of the hose, allows you to change suction for different cleaning jobs.

If you own these Kenmore pet friendly bagged upright vacuum cleaners, please share more details below to help others make an informed decision.

According to Kenmore customer service, the difference between Kenmore Intuition BU4020, BU4021, BU4022 and the one sold at official site is the color, the number of bags included, and what accessories are included. The machines are functionally the same.

images from Kenmore infomercials

• BU4020 is Red; sold at Amazon.com; comes with (1)Dusting Brush, (1)Upholstery Tool, (1)Crevice Tool, and (4)HEPA bags.
• BU4021 is Blue; sold at Target.com; comes with (1)Dusting Brush, (1)Upholstery Tool, (1)Crevice Tool, (1)Pet HandiMate Turbo Brush and (4) HEPA bags.
• BU4022 is Green; sold at many retailers websites such as homedepot.com, Amazon.com, wayfair.com and more; comes with (1)3-in-1 Combination Tool, (1)Pet HandiMate Turbo Brush, (1)Dusting Brush and (6)HEPA Bags.
• The one sold at kenmoreintuition.com is Green, comes with (1)3-in-1 Combination Tool, (1)Pet HandiMate Turbo Brush, (1)Upholstery Tool and (6)HEPA Bags.

All tools can be attached to the end of the wand and the handle.

• The 3-in-1 combination tool can be can be used as a crevice tool to clean in tight spaces such
  as between cushions, or as an upholstery tool to clean
  fabric surfaces such as sofa, or as a dusting brush to clean loose surfaces such as drapes.
• The Pet HandiMate® tool can pivot, you can use it to clean furniture, carpet or other fabric surfaces.

Kenmore Intuition Bagged Vacuum Models Specifications comparison:

Features you may want to know:

• No Touch Bag Disposal
  The hands-free operation and self-sealing bags do not require you touch the bag when empty.
  If you have a Shark Lift Away vacuum but hate all the maintenance you have to keep up with, then you can consider this Kenmore Intuition bagged vacuum which requires less maintenance work.
• AllergenSeal™ Technology
  In addition to the No Touch Bag Disposal Technology, these vacuums have Triple filtration including HEPA filter to trap allergens and 99.97% of dust particles (down to 0.3 microns), this makes the Kenmore Intuition a good vacuum for allergy and asthma sufferers.
• Lift-Up Technology
  This is similar to Shark Lift Away feature, you can lift away the canister part to tackle stair cleaning and above floor cleaning such as ceiling fan cleaning. This makes it versatile.
• Detachable Handle and Wand
  The removable handle and wand also make it more versatile for tackling different cleaning jobs and extend the reach.
• Bag Fill Level Indicator
  This indicator located on the top of the canister tells you when the bag is full and needs replacing.
• Swivel Steering
  The cleaner head swivels for better maneuverability.
• Lightweight
  Weigh less than under 14 lbs, light as an upright vacuum. The lift up canister weighs about 8 pounds.
• Powerflow™ Technology
  Filling and compacting simultaneously, allows the bag to hold more, and maintain suction power.
• Headlight
  The lights on the nozzle illuminates dark spots and reveals hidden messes for a thorough clean.
• Brush On/Off
  There is a Brushroll On/Off control located on the top of the canister to let you turn on for cleaning carpeted surfaces or off for hard floor cleaning.
• Suction Control
  There is a suction control valve on the handle that allows you to open to reduce suction when less suction power is needed.