Two new doctors in the blogging house

Congratulations to Brian and MarkH, who have both just successfully defended their PhD theses*.
It’s interesting how the process of getting a PhD differs in different countries. As Mark explains in his post, in the US you don’t start with a specific research project in mind; part of the process is you working with your supervisor to come up with your own proposal. In the UK, and most other countries, you’re working on your thesis project (which has generally been thought up by your supervisor before they ever met you) from the very beginning. There’s certainly ways and opportunities to imprint your own ideas and vision on things if you’re so motivated (my PhD project ended up being much broader in scope than originally envisaged), but it’s not quite the same thing as designing your own research programme from scratch – and that’s a valuable skill to take into your post-doc and beyond. On the negative side, this experience comes at the cost of 2 or 3 years’ worth of extra work.
There are also variations in the way you have to defend your thesis. My defence in the UK was in the form of a three or four hour, closed door discussion with my two examiners. In the US you get that too, but you also have to give a public presentation of your work to the entire department. Here in Africa, there is no defence at all – the thesis still gets to the external examiners, who send back a report with their suggested corrections.
I wonder how important these differences are. Is there an obvious difference between the sorts of post-doctoral student the different systems churn out? If there is, does it have a significant effect their later career trajectories?
*I’ve always wondered about this pluralisation – an intentional aural pun, or not?