How is the hard drive involved in UEFI

I am not trying to be a smart ass but if I knew the specifics I wouldn't have asked the question. According to the above comments it sounds pretty simple. If you use UEFI the drive must be GPT. Is there more to it than that?

   One rumor I have heard is that the boot partition is much, much bigger for Windows 8 and 10 because of UEFI but that is the reason for the question. How else is the hard drive involved with UEFI other than forcing the drive to be GPT?

here a nice article on the differences :  http://superuser.com/questions/496026/what-is-the-difference-in-boot-with-bios-and-boot-with-uefi

If you use UEFI the drive must be GPT

Only if the OS is Windows. On Windows you are also limited to the 64bit version. The 32bit version only supports MBR boot disks. With Linux it can be either, MBR or GPT. It isn't an UEFI problem, but rather a Windows problem and how m$ decided to build their OS.

On my disk I have an EFI partition that is 100MB in size, and another system reserved partition that is 128MB in size. I've setup Multiboot from Windows 7 Pro, Windows 8.1 Pro, and Windows 10 Pro and 2008r2. Windows 8.1, 10 and 2008r2 I have installed to a VHD file I boot from, only Windows 7 boots from an actual partition on the HD directly.

So... often times I wonder if some things that are new aren't the result of someone being bored :) Other than overcoming the 2TB hard drive limit what other advantages are the to UEFI?

The 2TB disk limit isn't anything that has to do with UEFI, it is an MBR limit, and as I mentioned earlier you can boot a PC using a conventional BIOS from a GPT disk as long as it isn't an m$ OS. With Linux this is easily done. It's only m$ OS's that don't work from a GPT disk in combination with a non UEFI BIOS.

Otherwise mainboards with UEFI BIOS's should boot much faster, some BIOS functions can be changed directly from within the OS with no need to reboot into the BIOS. There is also "Secureboot" which according to m$ should prevent malicious code be introduced into the boot code of an OS, although the real reason for secureboot really is to prevent other OS's from being installed.

>>  what other advantages are the to UEFI?   <<  read here : http://techpp.com/2013/12/19/uefi-vs-bios/
BIOS
- limited to 1 MB of memory,
- 16-bit instructions
- and MBR (Master Boot System) partitioning system which supports a maximum of 2 TB hard drives with only 4 partitions
UEFI
- modular design,
- can support 128 partitions and a whopping 8 ZB (that’s zettabytes) of hard disk space - -  - thanks to the newer GPT (GUID Partition Table).
-   UEFI provides closer integration with the operating system, as seen with the Advanced Startup Options from Windows 8.
- Secure Boot is another UEFI feature that helps with security. It allows users to install only registered operating systems.