Voyages of discovery? (spoilers for all RotE books)

[Albertosaurus Rex]

It is rather doubtful that soldier son is on the same world... The level of technology is far too high there when compared to RotE... Soldier son has rather advanced firearms, while RotE only uses arrows and catapults... It is very rare for any world to have both early-mid medieval technological development as well as far later epochs... The styles of these two worlds are also far different...

Still not having read Soldier Son yet, I must tread very carefully here, but... isn't the point here that the two "worlds" could be seperated by something like a great sea? If that is the case, it would account for the differences in technology: in isolation from each other, they develop differently.