[MereInterest]

The US frequently merges the masters and PhD programs into a single 4-7 year program, rather than a 2-year masters followed by 2-5 year PhD program. The comprehensive exams for PhDs are typically at the end of the first two years, and cover material similar to that of a masters.

The two are pretty much equivalent, but with different names.

[snotrockets]

To quote my advisor, who was a faculty member both sides of the Atlantic, while the path is different, by the end of the PhD, you mostly done the same amount of work, regardless of which system you participated in.