There's not a lot to tell really. The interior's artist has four times the number of pixels to work with over any given area. So text is much clearer, rivets, screws etc is more detailed, lines less blocky looking, shading more graduated and so on.
All future planes and GVs will have the new 2048 interior art including the next batch. I doubt that HTC would bother to update older interiors to 2048. It wouldn't be worth the time involved.