The difference between Hoover S2220 and S2200 are:
Hoover S2200 vs S2220
images from manufacturer

They are in different colors.

The S2220 has a motorized brushroll that can be turned off whereas the S2200 does not have a beater bar.

On hoover.com product pages, it states that the S2220 has a 8.2 amp motor while the S2200 has a 6.8 amp motor.

The S2220 is a little more expensive than the S2200, it is priced at $59.99 whereas the S2200 is priced at $49.99 at hoover.com (prices checked on July 12, 2013)

Otherwise, they are identical.

They are bagless, have no bag to change.

They have 20 ft power cord.

They feature slot for hanging up.

They carry one year limited warranty.

120 Volts.

3 level height adjustments.

9-inch Nozzle Width.

They have no attachments, no headlight, no speed settings.

Learn more by downloading manuals:
Hoover S2220 manual: http://hoover.com/file/617/
S2200 manual download: http://hoover.com/file/618/

If you know more difference between Hoover S2200 and S2220, please share here.