Difference between ASRock Z170A-X1 and ASRock Z170A-X1 ATX/3.1?

[sharksfin]

What's the difference between ASRock Z170A-X1 ATX LGA1151 Motherboard (Z170A-X1) and ASRock Z170A-X1/3.1 ATX LGA1151 Motherboard (Z170A-X1/3.1)?

 

[Dark Lord of Tech]

USB 3.1 spec was added.

They did the same thing to the Z97 A awhile back.
Asus Z97-A/USB 3.1

 

[sharksfin]

Is that the only difference?

 

[sharksfin]

I looked at http://www.asrock.com/mb/Intel/Z170A-X13.1/?cat=Specifications and http://www.asrock.com/mb/Intel/Z170A-X1/?cat=Specifications side by side using Opera browser, and I Ctrl-Tabbed as I scrolled down. There's two things that the 3.1" motherboard has that the non-3.1 doesn't:

1 x USB 3.1 Type-A Port (10 Gb/s)
1 x USB 3.1 Type-C Port (10 Gb/s).

 

[ArtPog]

Does anyone know the precise dimensions (L x W) of the ASRock Z170A-X1/3.1 MB? Thanks.