There is no difference between the box store and dealer models components (at least for Deere), but note these things:
- Box stores will only sell the "lower" series models. You can get these at the dealer too, but they also carry the higher-level models. In your example, the 655 is levels above what is sold by the box stores so you can't really compare the two.
- The biggest thing is SERVICE! As Topzide said, no box store services the name-brand models. They send you back to the dealer, and the dealer doesn't want anything to do with it (why would they when you could have bought the same thing, for the same price, directly from them??)
Tell you neighbor if he wants a Deere model that is at a box store, go to his closest JD dealer. They will always match the price on those models, then you get on the good side of the dealer since you bought directly through them. There is absolutely no reason to buy from a box store if the same model is available at the local dealer (people usually assume the box store is cheaper without ever checking with the dealer).