train model, question!

Two questions actually!
First is that you said at the end of the video we could ask you if we wondering why you prefer the class X < Struct syntax over X = Struct.new, I'd love to hear why!
Also, I wasn't sure what creating a passenger that has a train meant? I've been working with RoR for the past week and all I can think of is :train :belongs_to :person, I know I'm overcomplicating it so could you just explain a little more what you're asking? Thanks so much! (Also if the pull request comment section isn't the proper place for this just let me know where it should go in the future!)