As Hillrider said, there has only been one standard in use throughout the world (except France (figures)) for many decades. However even within the same standard there is tolerance, so there will be some variation in fit. When Campagnolo started aluminum cranks they elected to keep the thread nearer to the lower size limit (as did other alloy crank makers) to ensure a tighter fit. It makes sense because aluminum threads have less strength than the same threads in steel, so good fit is more important.
Odds are that your other pedals have slightly larger pitch diameters
(how to measure) and so are just that extra bit too tight. I suggest you check that there are no dinged threads, and if not, grease them and gently force them in. Don't get carried away, and if the force needed is significant, or ramps up as you go deeper, stop.
It's barely possible that your Campy cranks were made for the French market and have the 14mm thread rather than the BSC/ISO thread.