Clevo P870DM-G or P775DM1-G

I'm not going to use SLI, but I have seen images of xmg u716 (775DM), and it seems the MXM module 980 is the smallest.

u716 (P775):



u726 (P870):



But in this review the performance is the same:

http://www.notebookcheck.net/Schenker-XMG-U716-Clevo-P775DM1-Notebook-Review.155740.0.html

What is the difference between these 2 modules?

Thanks, and sorry for my english.