The HD DVR set-top box has a higher storage capacity of up to 500 gigabytes. This means that it can save 300 hours of standard definition television, or 60 hours of HD television. The HD DVR has the same features as the DVR, with more storage capacity. It also is enabled with Dolby Digital 5.1 Surround Sound to give you the best sound quality to match your crisp HD picture on your TV.