There are considerable variations between 737's of the same series number. The British Airways 737-200 has a full Sperry dual autopilot and PDCS which is considerably more advanced than your basic 737-200.
With the Airbus on the other hand you would be hard pushed to see any immdediate differences between an A320 cockpit and an A330 cockpit, yet the A330 is a considerably larger aircraft. You fly them both in exactly the same way as well. The A330 has a little more momentum on the approach, a higher flare height and your sat further forward of the nosewheel for taxying. That is it!
As has been pointed out in other threads Airbus have got it right on this one. Boeing are still in the dark ages.