Having just ordered one. The bodies are the same, what's different are small cosmetic differences between the trim levels such as chrome mirrors (or for that matter larger mirrors for towing), chrome or body colored bumpers, and some models have LED tailamps while others don't. There's probably more but it doesn't come to mind, but you can see it all broken out in the brochure or go online to RamTrucks
Now that I'm rereading the question, I realize that my information cab be misconstrued. I don't think there are any differences in appearance between the gas and EcoDiesels. The only differences lie in the trim level regardless if it's a gas or EcoDiesel 1500. Maybe one difference would be the power bulge with the dual intakes for the Hemi? Do they still offer those hoods for the Hemi 1500's?