Different terrain generation - client vs server

I upgraded to 13w41b and the terrain generated in single player minecraft is not the same that generates in multiplayer. I've found a MESA biome that doesn't appear to get generated in multiplayer with the same seed (existing world). I didn't counter-check differences in other biomes, though. Also, the vanilla JAVA gui doesn't show any text either on the right side. I also tried to redownload all the files, tested it and got the same outcome.