WD My Passport comparison

I see another thread along this line but a bit older one, so might I ask again about the differences (if any) concerning the WD My Passport 750 gb and the WD My Passport Esssential 1tb. One of these is supposed to be a newer model than the other.

Has there been any updated info on that since August of this past year, when I think the older thread was begun. (Let’s not everyone rush in to answer at once please)

If you post the model number it would help. If you check the link below you will see that there are a lot of hard drives named passport. 

http://support.wdc.com/product/install.asp?level1=2&lang=en