I've found some confusion while reading the forum posts/gallery pics from European members. In Canada, they are called HPS, MV, MV/DX, MH, PSMH, and LPS. What is confusing is how European lamp makers call them HPL, HQI, SON, SON-T (just a few that I know).
What is what?

HPL, HQI, SON and SON-T are all generic names for that used in Europe for MV/DX, quartz MH, Elliptical diffused HPS and tubular clear HPS respectively (Philips HPL, Osram Powerstar HQI, Philips SON and Philips SON-T).
I personally still uses the names that used in NA (AkA HPS MV MH and LPS/SOX) except PSMH (I uses "pulse-start MH" or "probe start MH" names).

The designation used in Europe usually follow the designation used by manufacturers or in that given region. These are somewhat systematic, but there is nothing like one common designation system in Europe. But as the number of influencing manufacturers shrunk over time, there are no more than three systems used in Europe - Dutch (mainly Philips), German (mainly Osram) and British (some others). They do not collide with each other, are well known, so they all remain alive.
The tables are on the www.Lamptech.co.uk - I think they are quite extensive.

Dear child has many names 

I usually prefer names like HPS and MV etc. when talking about some lamp type in generally. I may switch to manufacturer specific name if talking about lamps made by one particular manufacturer. Like SON-T if talking about Philips HPS lamps.

Based on my experience, not many people in Finland use manufacturer specific names either without meaning particularly that manufacturers lamp. Many lamp type allready has somekind of nickname. Like High pressure sodium -> Suurpainenatriumlamppu(the official long name) -> Natriumlamppu(Could also mean LPS but since so uncommon here, no risk of misconception) -> Natikka.

Also due to one particular manufacturers strong presents in some countries, the manufacturers own product name could live on there more easely than others.