The only major difference I know of between the US and UK is that the UK is very exam-based while the US incorporates coursework as well. It's possible that these students know that they aren't good exam-takers and prefer the help of coursework for grades.
It depends on what you want to do, where you want to be, what degree you are pursuing. If you want to be close to family, Australia is better and they have good universities. If you're a good exam taker and want to be done with university in three years, the UK would be a good choice.

These are gross simplifications of the three systems, but you get the gist.