I've recently attended two PhD thesis defenses at Georgia Tech, which were quite different from a PhD thesis defense at TU Delft.
One of the first differences, is that the thesis itself is not fully completed and printed yet at Georgia Tech before the defense. In Delft, the thesis committee will give their input on the draft thesis before the defense, then the thesis is printed and after distribution of the printed dissertations, the defense itself can take place. At Georgia Tech, and I assume at other US universities, the defense takes place before the completion of the thesis.
The defense itself consists of a presentation which is open to the public, as well as the actual defense with the committee, behind closed doors.
The presentation is attended by the committee and lasts one hour. In this presentation, the defending PhD candidate receives enough time to explain his/her thesis work to its full extent. At TU Delft, the presentation only lasts 20 minutes, is not attended by the committee and has to be given "such that friends and family can actually understand what you've been doing all those years."
While a defense at TU Delft is very formal, is only held in the Senaatszaal of the Aula and involves a beadle and paranymphs, a defense at Georgia Tech is less formal. Also, at TU Delft, the defense and the actual graduation are merged into one ceremony, while at Georgia Tech the defense and commencement are separate, and months apart.
What seems to me an advantage of the system used at Georgia Tech, is the shorter time between the first completed draft of the thesis and 'being done' (which would mean the defense in Delft or the submission and acceptance of the thesis at Georgia Tech). At TU Delft, this seems to be a matter of months, while at Georgia Tech it is more a matter of weeks.