MacOS – Remote Management

By default, Mac OS uses VNC combined with a few extras (e.g. auto-discovery via Bonjour) when you use Screen Sharing, and in most cases this is all an average user needs. For system administrators however, there is usually a need for more control over the computers they support; therefore Apple provides "Apple Remote Desktop" (ARD) which offers a lot more control mechanisms (like terminal sessions, remote installation of software, remote shutdown, remote execution of automator scripts) and this is possible with groups of many computers at the same time. For this feature to work, SSH and remote management needs to be activated.

So in short: Screen Sharing is roughly equivalent to VNC, while Apple Remote Desktop is a "high-end" remote administration software which requires "Remote Management" to be turned on. There is also a difference in how incoming screen sharing requests are handled: with "Screen Sharing" enabled, if an observer connects with a user account that's different than the one currently logged in and clicks Share Display, the user needs to confirm before the screen is shared. With "Remote Management", the screen is immediately shared without a prompt appearing.

I found the following code in a file I didn't open for a long time. It enables Remote Login on a remote device. Save the script somewhere (from now on referred to as /path/to/script/). Copy the script to the other device.

tell application "System Preferences" to set current pane to pane "com.apple.preferences.sharing"
tell application "System Events" to tell process "System Preferences"
    click checkbox 1 of row 6 of table 1 of scroll area 1 of group 1 of window "Sharing"
end tell

This enables remote login. Now, to disable remote management and enable screen sharing, use the same script, but remove the 3rd line and add these 2 lines:

tell application "System Preferences" to set current pane to pane "com.apple.preferences.sharing"
tell application "System Events" to tell process "System Preferences"
    click checkbox 1 of row 7 of table 1 of scroll area 1 of group 1 of window "Sharing"
    click checkbox 1 of row 2 of table 1 of scroll area 1 of group 1 of window "Sharing"
end tell

To copy this script on the remote device, use scp (secure copy). To use scp type
scp /path/to/script username@IP.of.other.device:/some/path
OR
scp username@hostnameOfDevice:/some/path/
The second option (using the device hostname) requires that the devices are on a computer-to-computer network, so it will not work on a normal wifi network. You will see a prompt requesting the password of username. When you type the password, you will not see any text appear (obviously to prevent people from seeing the password).

Once it is copied, remotely log into the device:
ssh username@IP.of.other.device
OR
ssh username@hostnameOfDevice
Again, the use of the hostname requires computer-to-computer network. Once logged in, run the script using osascript /some/path/theScript.scpt (remember that using scp we copied the script to /some/path, this will be different on your device). This will disable remote management and enable screen sharing.
Good luck!