Variation in motherboards for snes cartridges ?

[Alnitak]

I was opening two different Japanese copies of Super Metroid a couple of days ago and noticed that the two motherboards differed. The cosmetically older looking game (no perfect sign of age, I know) had a smaller board, with fewer chips. One or two less if I remember. I've checked around forums and images so I could identify fake carts and I can't see any sign so far that these aren't official carts. I completed the older cart in a couple of hours, and besides the rare sound artefacts (which I've heard on other copies) it was fine. More than fine on a big fat CRT with RGB cable...

So what's the deal here ? I don't know of any other releases in japan of super metroid, the boxes don't seem to indicate one, as there was in the US and UK. Did Nintendo just stop making certain boards after the more capable ones became cheaper to produce ? Has anyone else experienced this with certain carts ?

[Guspaz]

There were many releases of most popular games, and there are a huge variety of PCBs:

http://www.snescentral.com/system.php