It is very easy to confuse these terms... due in large part to the fact that computer manufacturers often still refer to UEFI as BIOS themselves. It's not. UEFI replaced BIOS, but it included "legacy" support for older operating systems. And I do it too... I will refer you to "BIOS Settings" because it is best known by that term, even though it should more correctly be called, "UEFI Settings."´EFI´ - in opposite to UEFI - IS ´legacy BIOS´.
(Through that both settings - if available (UEFI) at all - needs to be done in the BIOS, there is no non-BIOS UEFI, despite of in the representations - what ever for with which intentions - it is said so, that UEFI would not (no more) be (called) BIOS, more specifically "there is no more ´such a thing´ as the BIOS" ...)
In older BIOSs - which is just EFI, but without extra labeled, because of there is not to switch to anything else there - so, there is no UEFI.
First in newer BIOSs it is possible to switch between EFI or UEFI.
(But both are (the) BIOS still. Correct ? Sorry, saying it twice.)
In the early period of transition from BIOS to UEFI, it was first called EFI... but then it became UEFI. So EFI is NOT "legacy BIOS" as you suggest. For all practical purposes, EFI and UEFI are the same thing. This new system replaced the legacy system known as BIOS. See UEFI History on Wikipedia for details.
Last edited: