Syslinux is actually a collection of different boot loaders for different situations:
SYSLINUX: Installs on FAT file systems
EXTLINUX: Installs on ext, btrfs, FAT, NTFS, XFS, UFS, and HFS file systems
ISOLINUX: Installs on CDs and DVDs
PXELINUX: A type of network bootloader
MEMDISK: Emulates a RAM disk for older operating systems like MS-DOS. It is usually used in conjunction with PXELINUX and ISOLINUX