777 is much noisier inside especially in the smaller rear cabin behind doors 2. It is the terrible a/c system that is so loud that you can hardly hear the 777 engines. Air quality on the 350s is also much better (humidity) and they have the cameras (tail / belly / front gear) which is quite a nice feature during the day. Overall the A350s are far superior in overall technology (because their development was some twenty years later than the 777) but you don't feel much of it inside as the QR 777s are relatively new and very well kept.