If by firmware you mean RUU,

firmwares are region coded because they contain radios specific to a region. Like an Asian ROM would have a radio best suited for the Asia region (even Asia ROM also can be sub-divided into ROMs for each country, like HK, S'pore, Taiwan etc to name a few common ones). Not that an European ROM wouldn't work in Asia, just maybe the radio performance might not be the best the manufacturer thinks it can be.

And some regional RUUs are carrier specific, meaning it contains carrier specific bundled softwares.

Feel free to correct me if I'm wrong.

Hi , may i know what is the latest operating system for samsung galaxy note? is it possible to upgrade it to jellybean ?