I haven't seen the explanation between the two and it seems to be one of the key differences between the z130 and the z140, but what is the fundamental difference between App Mode and Advanced App Mode?

Thanks for your help.

App mode is just to view the video from certain videos apps controlled from the phone. Advanced app mode includes the ability to control the apps right from the head unit's screen.

+1 for VBlue's comment as well App mode offers limited control of some applications such as youtube will show the video and allow you to start, stop, restart and skip to next.

The advanced app mode allows improved control from the screen on the applications that support it. The apps are listed on the Pioneer page for the app radio. A bit limited but on variety of app selection but growing.

http://pioneerelectronics.com/PUSA/Car/AppRadio/AppRadio+%28SPH-DA01%29