The newer machines have a replacement for the traditional BIOS called UEFI. You can run the (GPT) GUID Partition Tables (replacement for MBR- Master Boot Record) independently of UEFI, but they are all a part of the same technology advancement to replace the MBR and BIOS technologies. UEFI is required only if you have a disk larger than 2T. UEFI provides a power-on shell similar to the BIOS power on shell but with more options.
An advantage of UEFI is boot times. My boot time on my laptop is consistently under 30 seconds from power on to logon. However, that's with out whole disk encryption setup.
Additional information can be found at : http://en.wikipedia.org/wiki/UEFI