SFTP is an FTP protocol that runs on top of the SSH (Secure Shell) protocol, while SSL/TLS refers to standard FTP running on top of an SSL/TLS (Secure Sockets Layer/Transport Layer Security) connection. SSL/TLS provides 128-256 bit encryption. SSH provides 128-256 bit encryption as well.
Sidenote to this. I know filezilla server is a popular FTP server application. HOWEVER!!! It does not support SFTP currently and is not in development at the moment and probably never will support this.
