You are homesick, as anyone would be. That is part, maybe most, of the reason for your thinking this way. People of your age in Britain get homesick when they are sent away to school, and that is when they are in their own country! It is not surprising that you are.
Every boarding school has rules and every one of them feels like prison ! That's life. But there are benefits, which you may not see yet, in being there.
Your father had good reason for sending you to an Australian school; he could have sent you anywhere in the world, but he chose that one. If Russia was better, he'd have sent you to school there. One reason, undoubtedly, is that you need to be in an English speaking country. He knows that mastery of the English language only comes with being in a place where only English is spoken. You do not yet have that mastery. Once achieved, it will last you the rest of your life. You want to go to university in the US or Britain. You will need to be perfectly fluent in English to study there. Staying in Australia will produce that fluency. English classes in Russia certainly will not: they are not 24 hours a day, seven days a week, with no Russian spoken!
Do not worry about different systems of education; they are as good as each other. The US, for example, is slower than ours in Britain, in that their young people generally learn, in the first year at university, what we teach our students in their last years at school. The results are the same in the end. Russia's sounds closer to ours, Australia's closer to USA's.
My advice? Stay where you are!