The photo for DVLA will need to be updated at times depending on how recent is your passport. At 70 my passport was 3.5 years old so the DVLA new driving licence used that photo, as did the one issued when I was 73. But before my next DVLA licence I will be having my passport renewed.
But the passport photo contains the anti fraud markings and more data, that is why when you look at the passport some may think it is not a very clear photo. The prime purpose is the E-scanning and don't forget whilst that is going on your face is also being scanned. Bristol airport had such systems in place certainly in 2016, and your "scanned visage" tracked you as you moved around the terminal and was there to greet you at the Boarding Gate.