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No... it's not the language that matters. What matters is the SDK, the set of APIs available to the developer to call into the OS and libraries to get various tasks done. Windows Phone 8 and BB10 have effectively nothing in common in those areas, so BB10 apps absolutely cannot be deployed to Windows Phone 8, in general.
That said, sometimes one can use a tightly restricted subset of the available APIs and build an app that can be re-targetted fairly easily. Using WebWorks (HTML5 stuff) may get you some of the way there, and there are third-party frameworks that can probably get you most of the way there. I'm not familiar with names and details so I'll let others comment on that.
In a very simple sense, however, you could never deploy *exactly* the same app because the packaging is different. BB10 apps are packaged as ".bar" files, with a certain set of contents, whereas Windows apps are something else... It's like how a ".exe" file will run fine on DOS/Windows, but cannot be used on a Linux platform, even if 100% of the code contained therein is compatible.