Look at the frame (below cockpit window) that draws the nose cross sectional shape of the B737, it is not perfectly a circle, but a little rectangular shape. While on the A320, the nose cross-sectional shape is nearly a perfect circle.
What is the difference between these two? Does it have to do with the instruments built in the nose? Which design creates less drag? How does the change in nose cross-sectional shape affect the aerodynamic properties?
(plus the B737 nose is more pointy than the A320's, the A320 and almost all Airbus planes have a blunt nose compared to Boeing aircraft)