Okay kiddo, so Moby Dick is a really big white whale. He's the star of a book story written by a man named Herman Melville. Moby Dick is a very important whale in the book because he represents something different for each character.
The Rhine is a big river that goes through many countries in Europe. It's also important because it connects a lot of places together.
But I don't think Moby Dick and the Rhine are related, they're two completely different things. One is a book character and the other is a river.