Im trying to make safe and secure bitcoin paper wallets and the only Ubuntu live cd that will work is the 13.10 version ( Ubuntu 12.04 wont boot at all matter what on my new MacBook Retina that has not been taken online yet ). Is "trying out" Ubuntu 13.10 on a USB drive through EFI as safe and secure as Ubuntu 12.04? Will it save my files/data at all? cause that's exactly what I wouldn't want. My MacBook pro will only boot Ubuntu through "EFI" mode while holding ALT when starting up the laptop, There is 2 options, Windows, and EFI. When I click the Windows boot option it won't detect that there is Ubuntu on that USB so Ubuntu will only start up and work while booting through EFI. What's the difference with EFI btw? And when it loads up the screen, its so small that you can barely see your cursor. How do I fix the size of the screen layout as well?? Thanks, Sky
EFI is a way of booting operating systems, like BIOS. Generally speaking, Windows will boot using BIOS, while Mac and Linux will boot using EFI (or UEFI). I believe that you can now get Windows to boot using EFI as well though (and you can also boot Linux using BIOS), so it's not quite as simplistic as I'm suggesting.
If you can boot it with the "EFI" option but not the "Windows" option, just use the "EFI" option.
Regarding saving files, this will depend on what files you create and how. If you are using ubuntu's "Try it" option, then as long as you aren't saving the files to the physical drive, then you will be fine. As soon as you reboot the computer (or turn it off), those files will be gone.