I have always been confused about this. At flight school we were told that 2/3rds of a wing's lift came from the top surface 'sucking' the wing upwards - owing to the air speeding up over the top lowering its pressure relative to the air underneath the wing.
But when looking at a propellor in flight school and commenting that since it has a similar profile to a wing, does the propellor mostly 'suck' the aircraft along?, I was told oh no, a propellor works by pushing air behind it. And it manifestly does push air behind it.
And more recently I have seen it asserted that an aircraft flies by its wings pushing down the same weight of air as the aircraft weighs, and certainly a helicopter's blades do push air down.
So, which is it, or do wing and propellor do both?