If you intend to come to Australia as an IMG, you would need to pass the AMC exams. The wait list to get both parts completed can be 2-3 years. You are then eligible to have registration (provided you completed your internship in your home country). You can then obtain a job as a JHO in an Australian hospital and compete for advanced training position, provided that you have permanent residency - which can take 2 years after you have arrived in Australia.
In contrast - for licensure in the USA, you will need to have passed steps I-III. You can then apply for a residency, although as an IMG many of the subspecialties can be extremely difficult to obtain (as they would in in Australia). You would have direct entry into your field of practice and would not have JHO/PHO years to complete as you would in Australia.
There is also the whole 10 year moratorium thing in Australia that is not applicable in the USA.
At the end of the day - you need to decide where you want to practice. Neither pathway or medical system is better, merely different in the way they obtain trainees and allow for licensure, and, perhaps more importantly, what they allow you to do once you have completed training.
Let's say you are a superstar - you decide to go to Australia, pass the AMC exams, get a job, 2 years later go into surgery (a 5 year program) - pass your exams before you complete - well, you have only had 7 years of licensure and you are required to go rural/area of need for a further 3 years. It would be difficult to set up practice in a capital city. Conversely, if you went to the USA - you would go straight into a surgery program, complete it in 5 years (instead of 7) and be eligible to practice anywhere, without restrictions. That being said, you will make substantially less in training and likely in practice in the USA. Both have their pros and cons. Look at the cultures and opportunities in practice (especially as an IMG), focus less on the $$$ (as you'll do fine in either system) and see where you heart and family obligations take you.
Conversely, you could stay in Iran, obtain your training there and provide needed medical services to your fellow countrymen and women. They did, after all, help pay for your medical education.
