Some Googling indicates that the difference is that the Australian technical specifications that the radio must meet are slightly tighter (better) than overseas, allowing use of the radio both in the air and for ground use (some manufacturer's models are restricted to airborne use only).
That suggests that Icom Japan just needs to make minor changes to the circuitry and the radio will meet both the Australian specifications, and slightly exceed those of overseas countries.
So if correct this does not mean a new model especially for Australia, but instead just some minor changes - improvements - to the current model.