1. Are they both from the same seller? And is one used and the other not? There's no difference in operating features between these Legacy versions so any price difference must reflect something else.
2. You mention comparing the Pioneer set with the Mark Twain version but there were three sets that Lionel catalogued as "Pioneer"; one was a Christmas version (red stripe), one Lionel Lines (blue stripe) and one with no painted stripe like the original Burlington Zephyr. Not sure how well the novelty versions actually sold as compared to the other two although I suppose it's possible the Mark Twain was more sought after than the others - but see point 3 below.
3. I looked at these sets carefully when they came out and got the Mark Twain version. That version of course has specific names for the engine and cars that are meant to correspond to the prototype but somehow Lionel messed up one of the names so that it reads "Huckleberry Fin" instead of "Finn." Annoying, that, as the name plates themselves are moulded in features and correcting the spelling is not really an option.
