The Dyson Ball upright is full size whereas the Small Ball upright is smaller, lighter to carry and saves more storage space than the full size Ball. If you are deciding between these 2, the Ball fits those big house whereas the Small Ball is for smaller space. Below is the comparison info that provides more details.
The Ball is much heavier, it weighs 17.32 lbs versus 12.15 lbs on the Small Ball.
The Ball has a suction power of 270 air watts whereas the Small Ball has 150 air watt suction power.
Dust Cup Capacity
The Ball has a much larger bin, it holds up to 0.55 gallons while the Small Ball holds only 0.21 gallons.
The Small Ball has a suction control slider on top of the cleaner head, it seems that the Ball does not have this slider.
The Ball features HEPA filtration whereas the Small Ball does not.
The Dyson Ball features Radial Root Cyclone technology while the Small Ball uses 2 Tier Radial cyclone.
The Ball has a 30ft. cord versus 31ft. on the Small Ball.
The Ball has a max reach of 51ft versus 42ft on the Small Ball.
The Ball is bulkier, its dimensions are 42.4″ x 13.4″ x 15.4″ whereas the Small Ball dimensions are 31.8″ x 11.0″ x 14.1″.
The included accessories vary depending on which versions you buy.
They have self-adjusting cleaner head that automatically adjust for hard floors and carpeted surfaces;
ball technology for easy steering;
hygienic bin emptying that only requires a button push;
5 year limited warranty;
both cleaner head can be detached for removing blockage;
If you know more info about the Dyson Ball and Small Ball upright vacuum cleaners, please share.