The sound quality is different. The Athearns (later production ones) have better sound as the sound chamber is built into the frame. The Intermountain simply has a loose speaker with a backing on it as an enclosure.
On a related note, Athearn released a bunch of preproduction photos of their upcoming Genesis GEVOs based on the Tower 55 tooling.
Just like M&Ms and Santa Claus, they do exist! Here are a few pictures of our upcoming early production ES44AC GEVO. Once we receive painted samples, we’ll make the official announcement with part numbers, pricing, and ETAs.
Disclaimer: This model was assembled from first test shots for initial evaluation in the R&D process. Production will have improved fit and appearance to meet Genesis standards. The test model does not represent a specific roadname.