difference between a 5 v 1a and 5v 0.65a hd
The small laptop drive consumes 5 watts of power (5V*1A).

The larger desktop drive consumes 9.25 watts of power (5V*0.65A + 12V*0.5A).

The desktop drive probably has a larger motor to spin the larger platters and a larger servo to move the heads over a longer distance. Desktop drive traditionally use 12 volt for the motor fo efficiency. However, laptops generally do not provide 12 volts for the hard drives so their smaller motors run off of the 5 volts needed by the rest of the drive.