Difference between two models by WD ?

[Fookraa]

I am planning to buy a 2 TB model of portable hard drive (USB powered only )..

My long lasting search landed me on two models by WD:
1. My Passport
2. My Passport Ultra

My local market has a price difference of $45 between the two, MyPassport being the cheaper model; My Passport Ultra is $176 approx in my local market..
However the specs on the official website of WD show both of them exactly the same except for a minute difference in physical dimensions.

I am interested in knowing the sound differenced between the two, and if possible, any other suggestions for 2TB+ portable drives(USB Powered)

 

[Devballs]

My passport ultra has SmartWare Pro and cloud backup, My passport does not.