Aside from the exterior differences, the only difference I'm seeing is that with the Laramie allows you to add the 730N radio.

What other differences are there?

 

Interior... Different leather package. Wood grain with badges vs painted and black. And of course, as you mentioned the exterior differences.

I also would not be to quick to think a 730N is not available in the sport. Right now build your own says that, but I recall last year build your own early in the 10 year had things missing.