Your brass overland car appears to have been made in the style of the actual Heritage car in that it has the panels in the lower sections of the doors below their windows, whereas the Walthers car does not (these are now like hen's teeth) I got the last 2 off M B Kleins when they were on clearance price. Here is a close up pic of those panels
Are they in fact ramps for the public to use to access the car when it's on show somewhere or just safety barriers because there are several pics of passengers looking out over them when the train is in motion (doors open). The car seems to have had a name change too, on rrpicturesarchives.net it's referred to as "Promontory", both before and after the Flag emblem was applied and I just went to the UP Heritage site (which has changed it's front page format since last looking) and there it's called "Council Bluffs". The name itself doesn't seem to appear on the side of it though.