[slavik81]

The Mac images are BIOS-only and are for older Macs that don't support EFI. Modern Macs can use the regular PC images, so the name is a little misleading. For example, from the Late-2013 MacBook Pro Ubuntu 13.10 install guide:

"The 2013 MacBook Pro can recognize multi-boot CD image (e.g., Ubuntu's official iso). So there is no need to use the "mac" iso image for installation. In fact, I recommend you avoid the "mac" iso image because it is a BIOS-boot only image and will force the Mac to enter BIOS emulation mode to install Ubuntu, which will need to be fixed to boot in its native EFI mode."

source: https://help.ubuntu.com/community/MacBookPro11-1/Saucy