In a pure series hybrid a gas engine acts a generator which charges a battery, which drives an electric motor, which provides power to the wheels.

In parallel hybrids, both the gas motor and the electric motor provide traction, sometimes simultaneously.

Parallel is more efficient if you're depending on gas often, as every conversion has losses. Toyota mostly sells hybrids you can't plug in, and the ones you can plug in are variants of the ones you can't, so they all share the same drivetrain.

As far as I know, such plug-in hybrids directly drive the car forward via the internal combustion engine, which is more efficient than using a (possibly smaller and simpler) engine to charge a battery which then moves the car via electric motors, which is what I understand the person that you're replying to to be describing, though I am not familiar with the specific Chinese cars in question, since those are not options available to me due to living in the United States.

Related, though not for plug-in hybrids: https://www.youtube.com/watch?v=KnUFH5GX_fI