NFS is the “Network File System” for Unix and Linux operating systems. It allows files to be shared transparently between servers, desktops, laptops etc. It is a client/server application that allows a user to view, store and update files on a remote computer as though they were on their own computer. Using NFS, the user or a system administrator can mount all or a portion of a file system.
CIFS is the “Common Internet File System” used by Windows operating systems for file sharing. CIFS uses the client/server programming model. A client program makes a request of a server program (usually in another computer) for access to a file or to pass a message to a program that runs in the server computer. The server takes the requested action and returns a response. CIFS is a public or open variation of the Server Message Block Protocol (SMB) developed and used by Microsoft, and it uses the TCP/IP protocol.
NFS and CIFS are the primary file systems used in NAS. Comparing CIFS vs. NFS, CIFS tends to be a bit more “chatty” in its communications. This may require file protocol optimization over a wide area network.