The Boeing 737 and Airbus A320 are similar in size and performance. They are direct competitors. Boeing seems to have eight flap settings (1, 2, 5, 10, 15, 25, 30, 40) whereas Airbus seems to have four flap settings (1, 2, 3, Full).
What is the reason for Boeing having twice the number of flap settings? I believe it is similar on other models as well.