I don't know how much digging you've done or how much pre-existing knowledge you have so I'll just lay it all out (cue the human beat box).
NTSC and PAL are names for two different standards for TV. Different number of lines of resolution (PAL has more, but not by much) and different refresh rates (50hz in PAL unless your equipment supports PAL60 and 60hz for NTSC).
NTSC and PAL are also names commonly used to refer to Europe as well as North America. That said Japan also uses NTSC and France uses SECAM as well as a smattering of other nations around the world using one or the other and sometimes an odd amalgam of them.
The SNES does its lockout job not just through the phsyical cartridge shape but also through a chip that can be disabled entirely HOWEVER some SNES games can detect when this has been disabled and will refuse to boot. The NES has a similar chip that can also be disabled. The SNES also apparently checks to see if it is in 50hz mode or 60hz mode which leads me to believe it works as a secondary check for region. Assuming that is accurate I'd wager Nintendo thought someone might transplant the lock out chip from one region's SNES to another leaving everything else in place.
tl;dr version: If it was released in Europe and the cart advertises itself as a European version then it should work in any SNES originally sold as European compatible. I can't think of any lockout that worked on a per-country basis.