The throttle-by-wire just uses an electronic accelerator pedal that tells the PCM how much throttle you want, then the PCM commands the throttle body to open that much. I much prefer a cable, but they simplified the whole system this way...No more cruise servo, IAC motor, etc.
BTW, looking at your pics, that black plastic cover hides your throttle cable. If you look at the pic of the '04, you can clearly see the electronic actuator and no throttle cable present.