Maybe my explanation was not clear. The Prius has TWO electric motors, thus it can do more things than a one-motor system.

Yeah, that was clear...NOT.
Anyway, let's see. How 'bout this: The Prius gas engine does indeed split it's power between the wheels and BOTH electric motors (all thru the planetary gear, power-split device). What this means is that many combinations of power can be happening, depending on your right foot. Every efficiency moment is taken into account.

There are times when the gas engine is turning the generator, which is then turning the big motor, completely not using any battery (series hybrid). At the same time it is also turning the wheels via the power-split device.

At times the gas engine is turning the wheels alone via the power-split device AND turning the generator to charge the battery, thus not using the big motor at all to help turn the wheels.

At times EVERYTHING is sent to the turning wheels: gas engine turning generator to power the big motor PLUS gas engine going to wheels PLUS battery sending it's help to power the big motor (parallel hybrid).

It's a complex but amazing system. IMHO, moreso than IMA. Just my opinion. I think it's cool that the power paths are many and varied to eek out all the efficiency.

'04 Seaside Pearl #7. Fumoto oil drain, mudflaps, rear bumper scuff protector & rear warn system, compass mirror, EV mode button, 8" subwoofer in right rear cubby & 6" subs under seats, power lumbar in the front seats, Coastaletech hitch w/ Aspen bike/snowboard rack. iPod2car, 2 amps, Alpine component speakers, and DVD video, solid 47 MPG @ 70000 miles.