Of the most significant changes:
Resolution is up to 4K or 8K instead of 1K.
The mesh and it's UV changed completely.
Placement of all parts of the fuselage are in different locations on the texture.
The vertical stabilizer UV is attached to the fuselage UV for easier painting.
Windows are no longer part of the mesh, they are part of the texture.
You can paint the underside (easy belly logos)
The XCF paintkit will make it easier to paint all over this, with placards, seams, windows etc on separate layers. Unless you made your liveries in a vector program such as Inkscape or make them as bitmap but with at a high resolution, you will not be able to reuse any of those since you can't scale them up.