You sure about the A300-600 carrying 380 pax??
The A330-200 is longer, by about 15 feet.
About the 767-400 against the A330, I would say the Airbus is the true widebody. You can't really compare the A330 with the 767-200s and -300s because they are quite shorter.
I would compare the 767-200 with the A310 and the 767-300 with the A300-600. Then again, the airbus planes are true widebodies.
And yes, Qatar was right to compare the A330-300 with the 777-200. On that respect though, the 777 is a larger widebody than the airbus.
But when all said is done, like someone said, both planes are proven and quite appreciated by pax. everywhere.