For me the differece between gobbledygook and jargon or cantis that in the latter two the words use may hide the meaning from the uninitiated listener, intentionally or otherwise. Gobbledygook as I have understood it is used to hide the fact that there is no, or very little, meaning. For example the technobabble used on many sci-fi shows. Like they said or the politition "I hear him talking but I don't hear him saying anything."