How does GNU GRUB differ from Erichs original GRUB?
GNU GRUB is the successor of Erich’s great GRUB. He couldn’t work on GRUB because of some other tasks, so the previous maintainer Gordon Matzigkeit took over the maintainership, and opened the development in order for everybody to participate it. Technically speaking, GNU GRUB has many features that are not seen in the original GRUB. For example, GNU GRUB can be installed on UNIX-like operating system (i.e. GNU/Linux) via the grub shell /sbin/grub, it supports Logical Block Address (LBA) mode that solves the 1024 cylinders problem, and TAB completes a filename when it’s unique. Of course, many bug fixes are done as well, so it is recommended to use GNU GRUB.