Complex sentence: The Palm IIIe shipped with Palm OS 3.1, same as what the Palm IIIx shipped with but unlike the Palm IIIx, the Palm IIIe did not have an upgradable Flash ROM but a permanent ROM instead so the Palm IIIe had no OS upgrade path.
Split into simpler sentences: The Palm IIIe shipped with Palm OS 3.1, same as what the Palm IIIx shipped with. However, unlike the Palm IIIx, the Palm IIIe did not have an upgradable Flash ROM, instead using a permanent ROM. As a result of this the Palm IIIe had no OS upgrade path.