Virtual Terminal (TTY) and X Session - Linux

ctrl+alt+f1 thru f6 are TTY (CLI) ctrl+alt+f7 thru f12 are X Sessions (GUI)

startx -- :1 & logout as usual to stop the session

startx - initialize an X session

DESCRIPTION The startx script is a front end to xinit(1) that provides a somewhat nicer user interface for running a single session of the X Window System. It is often run with no arguments.

   Arguments immediately following the startx command are used  to  start  a  client  in  the  same  manner  as
   xinit(1).   The special argument '--' marks the end of client arguments and the beginning of server options.
   It may be convenient to specify server options with startx to change on  a  per-session  basis  the  default
   color  depth, the server's notion of the number of dots-per-inch the display device presents, or take advan‐
   tage of a different server layout, as permitted by the Xorg(1) server and specified in the xorg.conf(5) con‐
   figuration.   Some examples of specifying server arguments follow; consult the manual page for your X server
   to determine which arguments are legal.

... https://www.youtube.com/watch?v=-LALnzOxsZI