The LCDs on iMac G5 and the early Intel iMacs do look exactly the same, even the electrical connectors are the same (LVDS is a standart after all) and the inverter boards are identical but they are NOT interchangeble!
One panel is labeled LM171W02 (TL)(B2) and the other LM171W02 (TT)(A1).
Unfortunately i can't remember which one is which. But i think a little google might help.
If you fit the G5 panel (i think it's the A1) into a CoreDuo or Core2Duo the machine will refuse to start.