Both use the terminal, but in different ways. A CLI interface uses the basic terminal functionality of writing and perhaps reading lines, or even simply accepti

Both use the terminal, but in different ways. A CLI interface uses the basic terminal functionality of writing and perhaps reading lines, or even simply accepting flags and running non-interactively. A TUI uses the terminal's advanced features, using the terminal as the basis for a kind of GUI, generally occupying the full area of the terminal. Vim, Midnight Commander, and htop have TUIs. They rely heavily on the terminal's 'control character' features to accomplish this. apt-get has a CLI, as its interactive IO is handled with printing lines and having the user submit lines (even if it's just the letter y). Somewhere in the middle are interfaces like bash and zsh which make light use of the terminal's advanced features for things like auto-complete, but which don't take over the whole terminal area. I'd count non-interactive applications like gcc and sort as command-line applications, although strictly speaking you could just as well use a graphical interface to configure their flags and run commands. See also https://en.wikipedia.org/wiki/Text-based_user_interface https://en.wikipedia.org/wiki/Text-based_user_interface