With the upgrade of the 737 to the Max model, what major changes are incorporated?
There are of course a lot of tiny changes that Boeing would have done to the aircraft that most of us wouldn't notice, but for brevity I've just included the major changes between the 737NG series and the upcoming 737MAX.


The CFM LEAP-1B engine replaces the current CFM56 engines. Some of the significant improvements in fuel efficiency (15% savings minus drag from larger engine touted by CFM) come from a much higher bypass ratio (from 5.3:1 to approximately 9:1) and materials that can tolerate higher temperatures. Chevrons (saw-toothed tips at the end of the nacelle) have also been included to reduce engine noise on takeoff.
The engine change required changes to the nose landing gear to allow enough clearance from the ground, extending the nose gear by about 8 inches (20cm) and modifying the nose gear bay to allow it to fit into the existing space.
The AT (Advanced Technology) winglets replace the 737NG's blended winglets. The AT winglet incorporates two portions, done to reduce the weight required (compared to a larger blended wingtip) while still reducing block fuel burn by about 1.5%.
Fly-by-wire spoiler system reduces the need for long cabling between the cockpit and the spoiler hydraulic actuators, saving weight, reducing stopping distance by quicker actuation and increasing the accuracy of the controls.
Redesigned tailcone and modifications to elevator to improve aerodynamics, removing the requirement for vortex generators (VGs), which improves predictability and control by making the air turbulent, but as a result increasing drag.