Same chip as the a7RII but different front end LSI that helps with speed and image quality. S-Log 3 and higher frame rates are the advantages over the A7 along with gamma assists. Not at liberty to say if the a7RII will get S-Log 3 in the future.
A mount translucent mirror focusing uses a hybrid phase detection system and affectively the 79 hybrid points are cross type points because of the way they work. There is also a new menu system that should be better than past Sony menu systems. Lets hope that they patch this into the a7 series.