Shell vs. Terminal
pbnetworks Inc. has published another article for Admin magazine online edition.
Shell access on a Unix-type server lets you send commands to a
target as a user of the system and get a response back (standard input
to a shell and standard output from that shell). This shell service is
limited; some commands will work and others will not. Windows shell
access has a similar limited command structure, and in this article, I
will explore how to navigate shell access and give some interesting tips
as well.

http://www.admin-magazine.com/Articles/Pen-Test-Tips-2