A SAN, or Storage Area Network, is a group of high speed networked storage devices that are shared among a group of servers. The benefit of a SAN over other networked storage devices such as a Networked Attached Storage (NAS) is that a SAN provides block level storage. This means that the servers are able to utilize the storage on the SAN just as if the storage was locally connected to the server despite the actual location of the storage being somewhere different.
SFTP, or SSH File Transfer Protocol, is a communications protocol that provides secure file transfer capabilities. SFTP is commonly used for sharing files in a corporate setting, web development and programming.
In rare cases, SFTP may also refer to Simple File Transfer Protocol. This is an unsecured file transfer protocol which is now largely unused.