The original European Kugelhopf (aka Gugelhupf) pan, which dates back centuries, is a mold pan designed to look like a Medieval hood or bonnet (Think Shakespeare or Henry VIII headwear designs) that was made of cast iron. It is heavy.
The original Bundt was designed at the request of European immigrants in America by Nordic Ware around 1950's to duplicate the Gugelhupf design in a lighter pan. It was a popular cake to these immigrants during Holidays and Weddings. Once it caught on in popularity new designs were added as we see in today's Bundt pans.
Lastly, a Rodon pan is any variation on that original Bundt pan or a Tube pan, as it is simply a "Ring Cake", whereas the Gugelhupf was vertical but slanted or "twisted." It was the only cake that followed a traditional design. The pictures above are not really accurate if your going for true design. All 3 would be a Bundt, the middle would be a Gugelhupf and all 3 could be used to make a Rodon, though for standard baking purposes all 3 are Bundt pans. Also Rodon is really just about the recipe and not the design (save for the ring shape), so any Bundt or Tube pan is acceptable. Gugelhupf is a yeast cake, whereas Rodon is not. Bundt is simply the pan variety, not a specific recipe.