The marketing scheme that calls HD Radio high-definition has pulled the wool over many eyes. HD Radio is just the brand name. It’s not really high-definition radio. What is high definition audio? Can it be classified as 7.1 channels of audio?
HD Radio is pretty much just digital radio. The quality exceeds analog because it has no interference or static. It is pretty much like listening to a CD. Also, with the digital format you can multi-cast, allowing more channels per channel. Analog signals take up too much bandwidth to have room to multi-cast.
So are you really getting high definition when you buy an HD radio? No, but the quality and programming is on par with satellite radio.