Also: maybe you remembered my reply as the other way around? (eg my explanation in the past). I see back in 2009 I said basically the same thing on a similar discussion But at the same time it IS a bit ambiguous -- I quoted Clare's FAQ which says hydrocephalus is an extreme form of dilated ventricles.
Although dilated ventricles are related to hydrocephalus I would think (or hope) they wouldn't be used interchangeably as so many would be then far more alarmed by having dilated ventricles noted on their scans -- it is so common! Real hydrocephalus is much rarer.
I agree that it is important to have a clarification and the area is very confusing! I will see if I can find out more on how neurologists view the two things too.