Elilo is a bootloader for systems that boot from a UEFI interface running in native (i.e. non-legacy) mode. In this mode, the firmware does not access the mbr at all but expects to find boot code on a special partition called the EFI System Partition or ESP, which must be formatted with a FAT32 filesystem. GRUB is compatible with this boot mode but LILO is not.
The elilo user interface has been designed to resemble lilo as closely as possible, although the internals of the program are very different. In particular, its configuration file, elilo.conf, uses the same syntax as the traditional lilo.conf, making it easy for former lilo users to make the transition.
LILO is filesystem-agnostic and understands only physical disk locations. These are written into it by /sbin/lilo, which needs to be run periodically as a normal program within Linux. Elilo however understands the vfat filesystem and can therefore handle any files that are located on the ESP. If kernels and their associated initrd images are placed on this partition, elilo can boot them. The elilo.conf file also needs to be on the ESP so that elilo can read it. This is an important difference from lilo.conf, which was kept in the /etc directory.