Everyone seemed to get hung up on the Pokemon aspect of that other thread, which wasn't even the purpose of it, so let's try this a different way. What games released on different platforms but with the same names are so different that they ought to be separate pages? I want to know where this cut off point is.
Episode 1 Racer:
Similarities: Both racing games. both share character and pod racer designs.
Differences: GB version features only two vehicles on the track at once. The game is top-down and the track never has any turns that are sharper than 90 degrees to the left or right of the top of the screen. Console version camers is behind the vehicle, there are 8 racers in each race, and tracks have elevation and ovals that circle back on themselves. There are more (most of them unlockable) racers, and vehicles are upgraded from race winnings.
Similarities: Both about a child entering the monster tower of Monsbaya to search for his father. Both mysterious dungeon-likes that focus on monster breeding. The monsters of the first 40 floors are mostly similar between them.
Differences: PlayStation version has dating aspects not present in GB version. GB version has twice as many monsters and monsters can be traded between players with a link cable. Every floor in the PS version is randomly generated and has evlevation, while the floors in the GB version are randomly selected from a pool for pre-made floors, and have no elevation. The GB version also has several events that can take place randomly on any floor of the tower, while the PS version only has a single event that can take place on the second floor. The sidequests related to taking quest items out of the dungeon are different for both games.
The Turok games:
Similarities: Same character and level designs.
Differences: One is an FPS, the others either side-scrolling shooter or top-down shooter. Completely different level layouts and weapon designs. Turok 3 GB even had vehicle sections.