There is a wide range of scientific computing libraries for Python. I'm fairly sure none of them have been ported over to Ruby. If you're not interested in tha

There is a wide range of scientific computing libraries for Python. I'm fairly sure none of them have been ported over to Ruby. If you're not interested in that not much. I'd say the only thing that's different between the two languages is when you ask "How do I write fast Ruby" the people who work on the VM and libraries yell back "Here are N fixes that improved the speed of the runtime two fold." When the same question is ask, but as "How do I write fast Python" there is a resounding "You write C/++, not Python." I think that's, in my opinion, the biggest differences between the languages: their community's and their community's attitude to optimizations.