A vibro-etcher uses a reciprocating carbide tool with a point, the marking is a series of dots closely spaced. The electro-pencil uses an electric arc, the part is placed on a plate which carries one side of the current and the pencil has the other side of the current. The handle of the pencil part is well insulated and the part will be hot enough after marking that you won't want to touch it. We used this identical machine in the toolroom to mark jigs and fixtures, it is old technology and has been around for quite a while.
