I'm not sure you can trust the outlets that claim cross qualification between the 777 and 787. Maybe that was Boeing's original intent!
This is from the Boeing website:
The 787 Dreamliner features a state-of-the-art flight deck that balances commonality with the latest enhancements. New technologies are integrated while still maintaining a significant amount of commonality with other Boeing airplanes, particularly the 777.
Familiar Boeing controls, displays and procedures all support shorter transition periods to the 787 from other Boeing family members, enabling efficient Mixed Fleet Flying.