What is UEFI
UEFI stands for Unified Extensible Firmware Interface. Most new motherboards consist of this new type. It has more advantages than using BIOS. Most importantly, it provides a user-friendly Graphical User Interface (GUI). BIOS provides a blue color screen with various options. The normal BIOS cannot recognize large storage drives. UEFI provides a good alternative to this issue and recognizes large storage drives.
UEFI is a new booting method that addresses the limitations of BIOS. It is managed by a group of chipset, hardware, system, firmware and OS vendors called UEFI Forum.
What is Legacy Boot
Legacy boot is the regular method of booting the system using BIOS. In brief, UEFI provides additional security features and fast processing on the computer. It offers a secure boot that can avoid loading boot time viruses.
Legacy Boot is the boot process used by BIOS firmware. It stores a list of installed storage devices that are bootable such as Floppy Disk Drives, Hard Disk Drives, Optical Disk Drives, etc. according to a configurable order of priority. When power on the computer, the BIOS performs Power On Self-Test (POST). Then the internal speaker makes a short single beep to indicate that the booting up is normal. The beep code helps to identify the code and to act on further troubleshooting.