There are only 2 schools in Australia that do JAA/EASA training.
One is in Western Australia, see
WAAC and there's one in Victoria,
Oxford.
I don't know the Melbourne set up WRT to Oxford. The WAAC has been going a little while now. Note, for the IR you will be doing that in the UK.
Not sure what you mean by ATPL in Europe? That's 1500 hours worth including 500 hours multi pilot. That's a tad expensive to fund.
If you want EASA/JAA, at this point in time, there are no accredited schools near Sydney. You'll have to go to Melbourne or Perth.
Australia is a bit more expensive than the US but a lot cheaper than the UK. You'll need to factor in airfares and accommodation/living expenses. The flying rules appear to be more similar in Australia than in the US. (I have only flown twice in the States. Both times leaving!)
No difference wrt to jobs etc. You'll be doing the IR in the UK/Europe and that's where the "fun" is. The biggest difference is how disciplined you are when "hour building". Faffing around versus setting decent challenges and goals. That's the difference.