Just the tone and language used.
I already agreed on that, the forum is just nicer if we're all just a bit polite, even if we don't like each other. And yes, that's not always so easy 
If you don't speak English, don't post on English sections.
There is:Quote
But there's no restrictions regarding that.
9. Discussions in the main boards must be in english. All other language discussions should be posted in the appropriate Local board.
You can argue up to what point bad English is still English, but it's obvious there is a line somewhere.