Really I think the difference was about on par with TOS > TMP refit (less so, going by the sets being unchanged), except the scope of the technology added was a lot greater. Weapons and defences that can shield from and compete with the rest of the 3189 Starfleet. A cloaking device. Programmable matter and detached warp nacelles (whatever difference they make), holodecks according to the mission logs. The entirely of Blade Runner's future LA, full of turbolifts zipping about all going nowhere.
You have to admit, that's a lot of refits!!