Generally speeking the 330-300 has no centre tank, therefore has a lower fuel capacity, therefore does not need to dump. The earlier -300 series aeroplanes had a lower MTOW of 215 tonnes as opposed to 230 tonnes or more for the -200 series. Typical MLW is 180 tonnes. Typical empty weight is 125 tonnes. Typical pax load is 35 tonnes.
If you can carry up to 109 tonnes of gas, you really need to be able to dump some - I have dumped on 2 occasions - ironically due to over fuelling prior to departure and an airframe swap.
The Airbus can land at MTOW but there are conditions - if you can dump, you will to prevent a possible maintenance inspection.