Telnet transfers all your data in clear text. That means someone sniffing the network could see your username and password.
SSH is encrypted since it creates a "tunnel". Contents inside this "tunnel" cannot be seen in clear text.
Telnet uses port 23 and SSH uses port 22
Telnet starts with a "t" and SSH starts with a "s"
I would always use SSH as it is more secure. The only reason I could see using Telnet would be on a simple public and anonymous computer where SSH is not available, or on your local PRIVATE LAN. For example, my local library allows me to renew and checkout books via telnet. Many Universities still use Telnet for simple public access. SSH does have some overhead because of the headers and contents being encrypted so it may somewhat affect your transfer rate. Heavy payload!
Last edited by Micro420; 11-22-2006 at 01:02 AM.