Some years ago, this was a much discussed subject. It seems the Kodak Gold 400 (and the 100/200) you would buy in the US, Europe, and Asia was not exactly the same. Kodak probably made slight modifications in respect to regional preferences (minor tweeks in the color balance). And yes, the Kodak Farbwelt 100/200/400 was basically the same as the Gold 100/200/400, and produced for the german market.
You may also have a look at
Kodak Farbwelt 100 ??? - Photo.net Film and Processing Forum
where they discussed that subject. There you will also find multiple links to more discussions elsewhere.