In what exact manner does an NTSC SNES game differ from being played on a PAL SNES+TV?

Question

I have a PAL SNES and a PAL CRT TV from 1989. I do not believe that it supports NTSC; it only says "50 Hz" on the back.

Some SNES games were never released in Europe (or anywhere which used PAL), so for certain games, such as Final Fantasy III (VI), there is only an NTSC version.

I have the NTSC American ROM of Final Fantasy III (VI) on my FXPAK PRO cartridge. I am able to start the game and it appears to run perfectly well on my setup, because the cartridge has some sort of NTSC-to-PAL converter mechanism built in.

This kind of "NTSC-to-PAL converter" existed back in the day as well, as a physical thing, but I never had one or knew anyone who had one, so it doesn't mean much to me.

Since the PAL and NTSC consoles are hardware-wise different, and the NTSC and PAL TV systems were quite a bit different, I have to assume that there are some differences compared to if I had run the game on an NTSC SNES with an NTSC-capable TV, but I have never been able to determine just what those differences are.

What exactly are those differences? How major/minor are they really? Is the game/music/logic speed slower, faster or the same for me? Is the resolution compensated for somehow? Are various special effects not displayed properly because of my PAL/50 Hz technology? Etc.

Prior to asking this question, I made an experiment and put the USA (NTSC) version of Super Mario Kart on the cartridge and tried that on my setup (and also the European/PAL one afterwards), which is a game I'm very familiar with, but was unable to discern any differences. (Although I did have it muted, so maybe the music is different speed. I also cannot fully trust that my eyes can determine minimal differences.)

Answer 1

The most common difference is the game speed. Games from the SNES era usually used the video frame clock as their timing signal, so an NTSC game running on PAL hardware will run 20% slower: it's designed around "60 frames = 1 second", but those 60 frames it's producing actually take 1.2 seconds to display.

It's likely that an NTSC game played on a PAL system will exhibit letterboxing or vertical compression of the image, since PAL frames are 625 lines tall while NTSC frames are only 525 lines.

Since the SNES uses an independently-clocked audio synthesis chip that runs at the same speed on all systems, sounds do not change pitch between PAL and NTSC, although the aforementioned timing difference means they do change speed.