NFS (NETWORKFILE System): ESXi hosts use this file-sharing protocol to share files with NAS devices. Storage devices such as NAS connect to networks and enable ESXi hosts to access files.
VMFS (Virtual MACHINE File System): In VMware vSphere, it is a block-level file system that stores virtual machine files. In vSphere 6.0, it can also store large files up to 64TB in SIZE.