Willisxdc is right, it is just language. The term BIOS is still used to in microsoft docs about Windows 10 boot manager. Your boot settings are described as “BIOS settings”. These lowlevel conventions change very slowly. The idea was to give the processor a minimal basic I/O system (BIOS) to communicate with console window, keyboard and boot device. UEFI implements BIOS conventions. UEFI has added remote access/boot and disk vendors create compliant drivers, that plug into the boot manager entries of BIOS. This allowed the old int21h BIOS calls be replaced by a Plug-And-Play system.