Both Hoover SH40060 and SH40080 are bagless canister vacuum cleaners, the difference between them are:

Hoover SH40080 vs SH40060
images from manufacturer

Cord Length: SH40080 has a longer cord.
The SH40080 has a cord length of 21 ft while the SH40060 has a 17 ft power cord.

Warranty:
The SH40080 is backed up with a 3 year limited warranty while the SH40060 carries one year limited warranty.

Color:
The Hoover SH40060 is mainly Billowy Blue Metallic and black while the SH40080 is mainly black and red.

Price: SH40060 is cheaper.
The SH40080 is priced at $249.99 at hoover.com while the SH40060 is priced at $149.99 (prices checked on June 06, 2013).

Similarities between Hoover SH40080 and SH40060:
They are corded and bagless;
they both feature auto cord retractor to rewinding the cord with only one button touching, and store the cord inside the unit nicely;
both have motorized nozzle and brush on/off switch for convenient cleaning between carpeting and hard surface floors;
features multi-cyclonic technology that separates dirt, provides good suction and reduce filter clogging problem;
have HEPA media filter to trap small dust particles and improve air quality;
Bottom Empty Dust Bin for easy dumping collected content without making your hands messy.;
both come with Crevice Tool for cleaning cracks, Dusting/Upholstery Brush for cleaning furniture, Telescoping Extension Wand for longer reach;
On board tools are stored under the handle for quick access when it is needed.
11-inch Nozzle Width;

Please share your opinions below if you know more difference between Hoover SH40060 and SH40080.