The difference between Hoover Air SH40070 and Air Pro SH40075 are as follows.
Dust Cup Capacity
The Hoover SH40075 can hold 2.5 liters while the SH40070 has a bin capacity of 1.98 liters.
The Hoover SH40075 has a longer cord which is 20 feet versus 17 feet on the SH40070.
According to info on hoover.com, the SH40075 cleaning path width is 12-inch while the SH40070 cleaning path is 11-inch.
According to hoover.com, both of them have 12 amps motor, but some users say that the SH40070 motor is 11 amps.
Otherwise, they are very similar.
These 2 are corded bagless canister vacuum cleaners with auto cord retractor, powered by Hoover’s WindTunnel 3 technology that create 3 channels of suctions to pick up debris and dirt, feature Steerable technology for navigating, the brusroll can be turn off when needed, they have suction control slider to adjust suction, have telescopic wand, hose and tool for above floor cleaning, have filter made with HEPA Media to trap tiny particles, and also come with a bare floor tool.
FYI, these 2 do not get good rating from buyers. If you are in the market for a canister vacuum, it would be better to consider another model.