Are there differences between CLI and TUI?

While the two terms are often used interchangeably, they are slightly different, since as RoVo pointed out, command-line is all about successive lines of text, which are commands. Think back to old teletype type of computers, where you could only type in command, and its output would come out on line of teletype paper.

For text user interface, we can reference such tools as Midnight Commander ( and some old folks will also know Norton Commander ) or ncdu or nano. In those you don't necessarily type in lines of commands, but navigate primitive menu made with ncurses library, and guess what. . . .such program uses text as representation of buttons,borders, etc. Take for instance, htop. The way memory and CPU usage bar represented is simply via # and * symbols.