nmcli : Short for network manager command line interface. This tool is useful when access to a graphical environment is not available and can also be used within scripts to make network configuration changes.
nmtui : Short for network manager text user interface. This tool can be run within any terminal window and allows changes to be made by making menu selections and entering data.
nm-connection-editor : A full graphical management tool providing access to most of the Network Manager configuration options. It can only be accessed through desktop or console.
systemsettings : This could be like GNOME settings(gnome-control-center) or KDE settings(systemsettings) in the desktop environment.