The UK is the only place in Europe where "billion" means 10^9; in Eastern European languages, there simply isn't an equivalent word, and everywhere else it means 10^12.
The Greek system parallels the short scale, but the terms themselves are derived from the myriad system; δισεκατομμύριο disekatommýrio, 10^9, literally reads twice-hundred-myriad.
The UK is the only place in Europe where "billion" means 10^9; in Eastern European languages, there simply isn't an equivalent word, and everywhere else it means 10^12.