PCIe slots macbook pro 13" and 15" (2015)

I Want to buy a new macbook pro.

But i did some research on the web about the new MBP (2015)

I red that in the new MBP early 2015, 13" their is a PCIe 3.0 x4 8.0GT/s (25.6Gbit/s)

and in the new MBP mid 2015, 15" their is a PCIe 2.0 x2 5.0GT/s (8.0Gbit/s)

Does it mean that the 13" has a very fastener flashstorage than the 15" MBP?

And is their anyone who can confirm this information? Because Apple, don't talk about the speed of the flash storage.