WD1002FAEX better power usage by alot?

So looking at getting a WD 64 Meg SATA 6 HD.   Checking all the FAEX models, the 1 TB drive lists:

6.8 Watts for Read/Write

6.1 for Idle

.70 for Sleep and StandBy

All the other FAEX drives list:

10.70 - Read/Write

8.20 - Idle

1.30 Sleep and StandBy

Why would the 1TB power usage be so different?

Which drives are you comparing the WD1002FAEX to? Im looking at a list of model number and am not able to see any other FAEX. faex.PNG