I have heard that the 722K has a different chip set but I've never read any elaboration as to which one may be better. What is the difference between the two hard drives? The 722K and its remote look different (worse in my opinion) 722 = built in OTA tuner. 722K offers $$$ dual ad on OTA tuner but nothing built in. Both take up to a 2GB external hard drive with no activation fee (for less than $100 = one of the best and smartest additions for anyone that does much recording). I have not seen any difference in the PQ between the 722 and 722K. The 722 is no longer being manufactured even though you may still see a few floating around in some warehouses. Not sure why the 722K was even born (maybe a bigger hard drive) as it seems to offer less than the 722 in it's base form.