Very interesting. There is definitely a fine line between the tow machines. I would say much more than between a lathe and a mill, but I guess you could argue that point as well.
Thanks all for sharing this.
There was a time when I use to research the origin of words. Fascinating study, for example the word "Starboard", which is the right side of a vessel (Ship or boat). The term comes from the fact that they use to have the rudder on the side of a ship not midships at the stern. It started as the Stearing Board and morphed into Starboard. Likewise Port is because if you had your steering board on the right side of the ship you did not want to put it against the dock and cause damage, so you would put the other side of the vessel against the dock or port, hence the "Port" side.
Never did find the origin for Captain. There is rumor that there was a chief whose name sounded like Captain from the Pacific Islands, a seafaring people. But no confirmation of the chief name related to the term.