They're more like the same airframe (fuselage, wings, undercarriage) with different fit an finish. Like different interior and possibly engines. The entertainme

They're more like the same airframe (fuselage, wings, undercarriage) with different fit an finish. Like different interior and possibly engines. The entertainment system is basically an add-on, it's separated both because it's not there in every configuration of the plane and also because it's supposed to be separated in order to be 100% sure that any failure there will not impact critical systems (like a short circuit, or an exploit). How exactly Boeing ensures this separation is another topic.