UH70105 vs UH70210
images from manufacturer

Let’s look at their titles first.
Hoover Model # UH70210 T-Series WindTunnel Pet Rewind Bagless Upright
Hoover Model # UH70105 T-Series WindTunnel Bagless Upright
Thier titles indicate that the major difference between Hoover UH70105 and UH70210 are the “PET” Feature and the “Rewind” fature.

Tools::
As a pet model, the UH70210 comes with pet tools that are made particularly for pets, including an Air Powered Pet Hand Tool and a Pet Upholstery Tool, they have rubber blades, that are made for removing hair from furniture and upholstery. While the UH70105 includes a common Air Driven Hand Tool and a combo Upholstery/Dusting tool that have no rubber blades for collecting pet hair.

Filtration:
The Hoover UH70210 is a pet vacuum, it features Carbon Filter for absorbing pet odors, so it gives you fresher air, while the UH70105 does not include Carbon Filter. They both have the HEPA filter and washable filter.

Auto Cord Retractor:
The UH70210 have the auto cord rewind feature which makes it a snap to retract the cord and more the cord stores neatly inside the vacuum, while the UH70105 has no auto cord winding and you have to manually wrap the cord on the back side after vacuuming.

Some other difference between them are:

Handle:
The handle of the UH70210 can be folded down, so it requires less space for storage whereas the handle on UH70105 cannot be folded.

Brushroll Shutoff:
The UH70210 has a “foot pedal” on the left side of its base. This pedal is for brush roll control. You can push it to get the brush spinning or stop the brush from rotating. So it fits your needs of cleaning both carpets/area rugs and bare floors. While the UH70105 has no brushroll shutoff mechanism.

Headlight:
The UH70210 vacuum with headlight for illuminating low light spots for efficiently cleaning while the UH70105 has no headlamp.

Weight: Hoover UH70210 is heavier than the UH70105.
The Hoover UH70210 weighs 17.8 pounds whereas the UH70105 weighs 15.7 pounds.

Price: The UH70210 is much more expensive than the UH70105.
UH70210 costs $159.99 while the UH70105 is priced at $109.99 at hoover.com. (prices checked on August 9, 2014)

Color:
They appear blue, but the UH70210 is a little lighter while the UH70105 is a bit grey.

The similarities:
they are upright vacuum with adjustable height, equip with 5 settings for various piles of carpeting;
features 12 amps motor rating;
carries 2 year limited warranty.
bagless, features transparent dust cup, and it is bottom empty.
average length stretch hose – 8 ft;
extension wand has a length of 12-inch;
27 ft power cord;
nozzle width is 13.5 inches.
have indicator that tells you when to check and clean dust bin and filter;
includes a small crevice tool.

To learn details, you can download the manuals:
UH70105 Manual: http://hoover.com/file/564/
UH70210 Manual: http://hoover.com/file/574/

We would greatly appreciate you sharing more info here if you know more difference between UH70105 and UH70210.