 
Amps is best described as how much current it requires to operate an electric motor. In theory the higher the Amperage the more powerful the motor, but that is not necessarily true.
Hoover explains it best with the confusing Cleaning effectiveness per amp definition:
Amps do not measure dirt removal, only the amount of electricity used. Cleaning Effectiveness Per Amp is determined by dividing this model's Cleaning Effectiveness* by its Amps.
*Cleaning Effectiveness is the percent value obtained from dividing:
(a) the geometric mean of the amount of embedded carpet dirt removed in testing under ASTM Test Method F60889, by
(b) the value 29 (the geometric mean of the midpoints of the % dirt pickup scales selected by Hoover as a reference for its rating system).
It must be nice to invent your own rating system to confuse your customers into believing that your highest priced upright is your best cleaner.
Geometric what ? Of the midpoints? Did they say 29 somewhere in there, why not 16.
any way in short amps are important in respect to the FAN SIZE
You can have a vacuum with 12 amps but if the fan is small it's not going to clean as well or as fast a model with 7.0 amps and a large fan.

