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 default interactive shell for the current user:
Check which shells are currently installed: cat /etc/shells
Set the new default shell: chsh
A non-interactive shell is used to execute system scripts or scripts that use #!/bin/sh shebang.
Debian uses Dash as the default non-interactive shell.
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. Therefore, many interactive features are not present in Dash, 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)