Well, that's easy! The Bachmann one hasn't got any moulded handrails on it at all like the old Airfix one has. Oh wait a sec... Erm, ok, well the Bachmann one has got a full representation of all the brake rigging and auto-gear equipment in the cab and externally so you won't be needing a Dart Castings kit. Oh wait a sec... Erm, ok, it has gone up to £70 already, so it must be an investment opportunity. And it's made by Bachmann.