The difference in designation may be wether or not it is CA or Federal emissions. Japan of course has their own emissions laws and standards but if you look at the part number it's basically the same.
My advice would be to call a US dealership, ask them the difference in part numbers between Federal/California emissions and wether or not it's Automatic/Manual.
FWIW I'm sure that the ECUs are internally the same. If they are manual drivetrain. The only difference would be in programming. For example
A California car may be equipped with an Air Pump to help cold start emissions. The ECU itself is the same but the programming either enables or disables the pins in the ECU itself when it's operating. Kinda like when you do an EGR delete. You're really just turning off codes so the computer doesn't check to see if that circuit is active