Originally Posted by
sfclearwater
ISO and English are IDENTICAL and, in fact ISO accepted English threading as it's standard. The numbers you quote are the same thing, just expressed a bit differently.
Italian threading is almost identical and English and Italian components will interchange. There is a minor difference in the apex angle of the threads with English threads having a 60° included angle and Italian threads a 55° angle. You can substitute one for another but it is not recommended you go back and forth. If you thread an English freewheel onto an Italian threaded hub, use English threaded freewheels thereafter.
French threading is different in both diameter and thread pitch from both English/ISO and Italian and won't interchange with either.