HD radio is a new type of radio transmission method that is digital. A traditional receiver will not pick it up. You must have an HD capable receiver. It normally provides a better sound quality but you must be within 15-25 miles of the radio station's tower for AM and FM. Of course, there are exceptions to this distance and an antenna can increase the distance.

Sound quality for AM is close to what you have currently for regular FM. Sound quality for FM can vary but is always good. A station can choose to divide its signal up into four stations rather than focus on improving the signal for its main station. If a station were to use full power for one HD signal, then it approaches CD quality.