Can just someone please clarify what are the differences (and which are just synonyms) between the words: console, shell, command line, terminal, etc. Thanks.

The console is a vga command line environment. A terminal is a console emulator, most of the time it's a GUI window.
The shell is a command interpreter (bash, sh)

From the linux dictionary, command line:
Note: it's also correct to say console and terminal are the same

Heh, heh, heh. These are somewhat interchangeable terms for different things depending on who is writing about what.

Terminal can mean an actual physical serial terminal, or refer to using a virtual terminal. If not refering to an actual serial terminal it usually implies using the CLI as opposed to the GUI.

When console is not refering to a physical root console it implies pretty much the same as terminal, CLI rather than GUI.

A shell is a CLI.

Command line implies using typed commands in a text interface as opposed to clicking on icons on a graphical interface.

CLI = command line interface
GUI = graphical user interface

And to make things "much clearer" people like to mix and match those terms as they see fit.

Good Luck.