> But it seem to differ by region/country and even ISP.

That's because there is no formal definition of when to use FTTH vs FTTP, just rough guidelines.

for most purposes they're equivalent. when getting into the details of a multi tenant residence vs a home we're getting into details that only matter to use networking nerds

For example all the FTTP apartment buildings i've lived in before I got my FTTH house had fiber all the way to the individual unit. There was no termination at the building split out to ethernet like some do, but my state also has a law against internet vendor lock in on apartments IIRC