If it's not LV-426 Ridley has done a terrible job differentiating the two moons, and the two SJ ships. I don't see any reason not to make the planet and the ship more different if they're supposed to be different. Put a third arm on the SJ ship - boom, now you know 100% they aren't the same. Make the moon a regular planet and not a moon around another ringed gas giant. Make it a desert planet or an ice planet or a lava planet (look how well locations were differentiated in Star Wars). Why would Ridley risk confusing the audience?
I would chalk up the minor differences in the ship structure etc. to the film making process. There were little changes to the Enterprise E between the Next Gen films too. There are little changes to the Imperial Star Destroyers between A New Hope and Empire. Only the super hard core fans noticed.
To me the gross similarities between LV 426, this moon, and the SJ ships are more important than the minor changes in detail.