Today two more trailers surface for PersonaQ: Shadow of the Labyrinth, which show off the differences between Safety/Easy and Normal/Hard/Risky modes and feature a bit of the party chat mechanic.
When playing Safety or Easy mode, your party receives more experience than normal, which strengthens them mush faster. Playing on Normal and above, your party takes more damage from enemies. As for Party Chat, when members in your party know each other well (ex: Chie and Yosuke), they will have special interactions. You can watch both trailers below to see these mechanics yourself.