IIRC, the surface details and lighting changed when Doug Trumbull was pulled onto the project late. There was some issue with the early VFX shots (from Apogee maybe? Can't remember) and he was brought in to make some adjustments. The post-Phase II/pre-TMP design showed up in a lot of early promotional artwork and merchandise. I think I may still have the jigsaw puzzle with that design, and the toy with removable components also was of the pre-TMP design. Looking at it side-to-side with the AMT-ERTL kit, which was in roughly the same scale, it always befuddled me as a kid why the two different layouts. Artwork I could understand - even then - I got that there was always a certain level of artistic interpretation and stylized deviation in painted works. But when my 8-year-old brain saw two real-life models, both nearly identical and yet very blatantly different, it really furrowed my brow back then. I guess I was as OCD about ship design as a child as I still am today.