I'm an undergrad in Australia, and at this stage I want to go on to do further study in maths (or maybe physics/CS, still have a few years till then).
Should I do so, I imagine that I will want to complete a PhD overseas. Possibly at a university in the US or maybe Oxbridge in the UK.
In Australia, PhDs typically take 3 or 4 years, and I would be eligible to go straight into a PhD upon completion of my undergraduate degree (it is research focused and includes an honours year, see here).
But, much of what I have found for overseas institutions has been in the range of 5-7 years, or maybe a 3-4 year PhD with a few years doing a master's degree beforehand.
Does this indicate that the level of rigour and amount of work produced is significantly different for various PhD programs, or is it the case that some programs are more relaxed and simply spread the same amount of work over a longer period of time?