The telnet command is used for interactive communication with another host using the TELNET protocol.

SSL telnet replaces normal telnet using SSL authentication and encryption. It interoperates with normal telnetd in both directions. It checks if the other side is also talking SSL, if not it falls back to normal telnet protocol.

Advantages over normal telnet: Your passwords and the data you send will not go in cleartext over the line. Nobody can get it with tcpdump or similar tools. With SSLtelnet you can also connect to https-server like https://www.mozilla.org. Just do 'telnet -z ssl www.mozilla.org 443'