Board Thread:Wiki/Forum Technical Support/@comment-33763020-20181103181003/@comment-27219153-20181103194549

In short, no, not by a longshot.

The terrain changes based on the seed. Regions generate according to the map (in fact, you can edit the map yourself and control where regions are generated), but each map pixel represents 128x128 blocks so the game will interpolate to get more natural region borders, this is done based on the seed. If you have a different seed, the borders will vary slightly. A few structures such as the Rammas Echor and the Ring of Isengard are fixed. There are also Fixed Mountains and Hills, which generate at the same coordinates, but the exact block placements are determined by the seed. Roads have a large list of coordinates indicating where they should generate, then they change terrain as necessary, but generate more or less at the same coordinates in every seed. Things like settlements have their placement determined by the seed, but the content of the settlement will change using the same seed.

Barangolo wrote: as we can see with some strange builds where the hill gets cut in half to make room for a city

During the generation of a settlement, the mod will shift entire columns of a chunk up or down to make the terrain flatter. So in your example, part of the hill was close enough to the settlement to be shifted down while the other part was not, making it look like it was cut in half. The game also checks beforehand to see if the terrain is suitable for a settlement to help minimize large terrain deformities.

TL;DR: Pretty much like vanilla seeds with a few specific exceptions, such as the map, Rammas Echor and the Ring of Isengard.