difference between types of telnets

[Reading Public Library, Reference Dept.]

This list has been helpful in the past, and I hope you can educate me again.
I have noticed that Netscape allows for 2 kinds of telnet application, plain
old telnet and TN3270.  Can anyone tell me the difference between these
telnets? What they are used for, etc.?

Eileen Stec, reference librarian
Reading Public Library
rplref at ptd.net