Heartland debuted the "Silverado by Bighorn" a few years ago. For the 2014 year model, being produced this fall, they have removed the Bighorn association, and the Silverado brand stands on its own. The "Silverado by Bighorn" has similar features and appointments to the Bighorn line, but it does not have ALL the features.
To me, it is similar to what Keystone has done... they have the "Mountaineer by Montana" to trade on name recognition of the Montana brand.
Dealers sometimes "fudge" the years when advertising to move product, but yes, it could be a 2014 made before late August, when I believe they made the switch. Be sure to check the manufacture date on the weight sticker on the off-door side of the coach to know for sure.