The five tiers

The further you go, the stranger it gets. Every tier changes the Overworld, the Nether and the End. How far away each tier starts depends on the server's preset.

Far Lands

The Far Lands shapes come from the original integer-overflow noise, recreated so they appear at whatever distance the server chooses. In the Nether, the bedrock roof weakens with distance until it's gone and the walls reach y256. In the End, the islands shatter into shards, plates and lattice.