Graphical shell is a rarely used term for a DesktopEnvironment.
Debian uses Bash as the default interactive shell.
The default interactive shell for newly created users can be set in /etc/adduser.conf.
To change the interactive shell for the current user:
Check which shells are currently installed: cat /etc/shells
Set the user's new shell: chsh
A non-interactive shell is used to execute scripts. It is not intended to be used interactively by a user, for example, in a terminal emulator, but rather focuses on speed and compatibility with standards.
The default non-interactive shell is /bin/sh which is a symbolic link to a real shell. Most system scripts use this, via the #!/bin/sh shebang.
Beginning with DebianSqueeze, Debian uses Dash as the target of the /bin/sh symlink. Dash lacks many of the features one would expect in an interactive shell, making it faster and more memory efficient than Bash.
Debian provides many different shells. A few notable shells include:
Bash - A very powerful shell, with very good interactive interface.
fish - Another friendly interactive shell.
tcsh - an enhanced version of Berkeley csh.
csh and tcsh should be avoided as scripting languages. See http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/
https://en.wikipedia.org/wiki/Comparison_of_command_shells - Comparison of command shells
https://wiki.archlinux.org/index.php/Command-line_shell - Command-line shell on Arch Linux wiki
(Archive) http:/www.looking-glass.org/shell.html - UNIX shell differences and how to change your shell (Monthly Posting)