I suspect that the DM has got it wrong as it should apply to all flights on EU carriers or originating in the EU. However the threshholds and amounts for payment are different for s/h and longhaul flights.
Right to compensation
1. Where reference is made to this Article, passengers shall receive compensation amounting to:
(a) EUR 250 for all flights of 1500 kilometres or less;
(b) EUR 400 for all intra-Community flights of more than 1500 kilometres, and for all other flights between 1500 and 3500 kilometres;
(c) EUR 600 for all flights not falling under (a) or (b).
In determining the distance, the basis shall be the last destination at which the denial of boarding or cancellation will delay the passenger's arrival after the scheduled time.
2. When passengers are offered re-routing to their final destination on an alternative flight pursuant to Article 8, the arrival time of which does not exceed the scheduled arrival time of the flight originally booked
(a) by two hours, in respect of all flights of 1500 kilometres or less; or
(b) by three hours, in respect of all intra-Community flights of more than 1500 kilometres and for all other flights between 1500 and 3500 kilometres; or
(c) by four hours, in respect of all flights not falling under (a) or (b),
the operating air carrier may reduce the compensation provided for in paragraph 1 by 50 %.
I would interpret this as meaning that a LON SYD would have to be delayed by >4 hours to invoke compensation of €600, which could be reduced by 50%.