Internal of My Passport Slim 2tb?

I’ve been trying to figure out what’s inside my My Passport Slim 2tb but I’m coming up with nothing.  I’m just wondering why it’s so thick, compared to the Seagate Backup Plus Slim 2tb.  Both of have the same storage capacity, but why is the Seagate only 0.48’’ thick and the WD is 0.70’’ thick?  That’s almost 50% thicker for the WD.  I thought that portable drives all had the same 2.5’’ size drive inside (as opposed to the big 3.5’’ storage you get in desktops), and the exterior would have approximately the same dimensions but wow… that’s clearly not the case haha.  Just wondering what happened here, and why WD can’t get it to be just as slim?

The 1TB version of the My Passport Slim is also 0.48"

My Passport Slim.JPG

The type of drive that comes inside is not specified as this might variate depending the model.

What kind of hard drive is inside a Western Digital external product?

http://wdc.custhelp.com/app/answers/detail/a_id/1704

Well yeah, that I knew.  But comparing across the same capacity, how come 2TB version of My Passport Slim is so much thicker than 0.48’’?  Are they using different drives or something?  There’s no way for me to find out, short of smashing my drive open haha?

That’s what it looks like.

As you cans see on the specs for 2.5 units, the bigger capacity drives are a little bit bigger.

http://www.wdc.com/en/products/internal/mobile/