HD = High Def, HDD = Hard Disk.
Mine is both - wouldn't buy another camera that wasn't HDD-based. No changing of tapes or discs - my mate got a Mini-DVD one and that's great. Except after half an hour he has to change the disc. I can get up to 900 minutes of 1080i video recorded and only ever have to change the battery to do it. And the supplied software is brilliant for just dumping it all onto a DVD - example I went to Farnborough airshow last week and got around an hour and a half of footage, full HD, plugged into laptop, couple of clicks later it was starting to burn a DVD with the video on.