Originally Posted by Globaliser

By "exact same flights", do you mean the booking the same flight numbers? Or will you get QR flight numbers if you book through QR, and BA flight numbers if you book through BA? For many purposes, if it's a different flight number it's a different flight, even if it's operated by the same aircraft.

One obvious point is that if you book BA flight numbers, you should get a Silver tier bonus of 50% of the normal Avios that a Blue member would earn (assuming that you will be Silver when you fly). You wouldn't get those Avios if you book QR flight numbers.

In addition, which booking class would you be booked into through each route? The earning rate depends on the booking class. In the most extreme difference in business class, for example, you would earn 75% of flown miles if booked into P class on a QR flight number, but you would earn 250% of flown miles (+ 50% extra as your Silver tier bonus = total 375%) if booked into D class on a BA flight number.