We will show you some difference between Shark NV80 and NV356E to help you choose the better one that fits your home cleaning needs.
NV356E vs NV80

Lift Away Canister
One of the key difference between them is the Lift Away Design on the Shark Navigator Lift-Away Professional Upright NV356E which the NV80 does not feature.
The canister on the NV356E is detachable that makes it ideal for portable cleaning such as vacuuming stairs, above floor cleaning, and hard to reach areas.

Bare Floor Tool
The NV356E comes with a Dust Away Hard Floor Attachment with 2 Microfiber Pads that the Shark Navigator Professional NV80 does not include.
The Dust Away Hard Floor Attachment with the microfiber pad are designed for dry floor cleaning, it picks up and wipes away debris and particles from bare floors.

Other Tools
The NV356E comes with an 8-inch Crevice Tool, 24-inch Crevice Tool, Dusting Brush, and Pet Hair Power Brush.
While the NV80 comes with a 5.5-inch Crevice Tool, 16-inch Crevice Tool, Dusting Brush, and Pet Hair Power Brush.

Wand Amount
The NV356E comes with a extension wand while the NV80 comes with a cleaning wand without handle and a cleaning wand with handle.

Handle
The handle on the NV80 is fixed while the handle on the NV356E is detachable. While doing stair cleaning and above floor cleaning with the NV356E, you can detach its handle from the vacuum body, then attach tools such as pet power brush and crevice tool to it to get the cleaning job done.

Weight
The NV356E is lighter.

Dust Cup Capacity
The NV80 has Shark’s largest dust cup that is larger than the dust cup on NV356E.

Similarites:
10 amps;
both of them have the Anti-Allergen Complete Seal Technology combined with HEPA filtration;
have the swivel steering;
motorized brush roll and shutoff;
suction release to regulate the suction power;
30-foot power cord, manual winding;
and backed by a 5 year warranty.

If you want the portable cleaning ability, then you should buy the lift away NV356E; if you like a larger dust cup, then choose the NV80 with Mega XL Capacity Dust Cup.

Below we list some of the difference between Shark NV70 and NV44, hope the info helps.
NV44 vs NV70
images from manufacturer

Swivel Steering:
The steering feature might be something that many people would take into consideration.
The Shark Navigator Plus 2X Capacity NV44 is not equipped with the swivel technology. While the Shark Navigator DLX Upright Vacuum NV70 features the swivel steering that allows you to maneuver around obstacles more easily.

Filter:
The NV44 has no HEPA filtration while the NV70 has a HEPA filter.

Dust Bin Capacity:
The NV70 has a larger dust cup which 3 times the capacity of the original Navigator while the dust cup capacity on the NV44 is twice that of the original Navigator.

Included Tools:
The NV44 comes with a Crevice Tool, Dusting Brush, and Pet Hair Power Brush.
The NV70 comes with a short Crevice Tool which is 5.5″, a long Crevice Tool which is 16″, Dusting Brush, and Pet Power Brush.

Cost:
The NV70 is more expensive.

Color:
The NV44 is lavender while the NV70 comes in gold.

Both of them have the same power specs: 120V, 1200 watts, 10 amps,60Hz.

image from manufacturer

According to the replies from Shark customer support, the Dust Bin Capacity is the only difference between Shark NV44 and NV22/NV22L, the Shark Shark Navigator Deluxe Upright Bagless Vacuum NV44 dust cup double the capacity of the NV22/NV22L.

The Shark Navigator Upright Bagless NV22 and NV22L are exactly the same machine, however, their colors are different, the NV22 comes in blue while the NV22L is in lavender color.

If you care about the accessories, here is more detail about the tools. The NV22 (sold at walmart) has only 2 tools: a dusting brush and a 5.5″ crevice tool; besides these 2 tools,the NV22L may come with a pet power brush, or a pet power brush and a 24 inches crevice tool, depends on where you buy. Some may include the 24″ crevice tool while others may not.
The NV44 comes with a pet power brush, dusting brush and the short crevice tool.

Shark official site sharkclean.com does not prodive any info about the NV44, such as specs, accessories and manual pdf download link, so you’d better contact their customer support for requiring any info you want to know before buying one, in case some parts need replacement or anything similar. If they do not sell the replacement parts, that will be a problem.

If you like the large dust cup, you can also have a look at the NV70 or NV80, they have even larger dust cup than the NV44.