The difference is often how it functions. Imagine you had a wireless keyboard, that you hooked up to multiple computers. Every movement you made and key you pressed would be relayed to multiple computers and thus multiple characters. The programs available often just make that task a bit easier and not require multiple systems, depending on how beefy your system is. Not a lot of systems can manage to run multiple clients.
Pressing 1 key and taking 5 actions on a single character/client is different as it allows a functionality that is not intended within the game.
Q:Automation(n): : automatically controlled operation of an apparatus, process, or system by mechanical or electronic devices that take the place of human labor
By key cloning or otherwise splitting the signal, even with hardware, you have removed the manual labor requirement of hitting 5 separate keys. You have automated the process on 4 out of 5 machines.
A:By that definition a macro, available in-game, could be considered automation. A macro will often do more than one thing, but no more than the system allows. Additionally, a keycloning program can do the same thing as if you were to attach a single keyboard to multiple computers. Which could not be considered automation anymore than if one keyboard were to control a single character. Otherwise no one would be able to play at all.
Automation in this case is to operate a single or multiple characters without direct input.