A NX 1600 is just the model down from the NX 2000, It has a smaller engine, no fog lights, no spoiler maybe ? cant remember, oh yeah and it has smaller brake set up too.
And maybe some other things too. But cant remember off the top of my head
NX 1600 engines are horrible. Reliability is much lower then The NX 2000. Don't waste your time on NX 1600 purchasing, unless you have no choice. Smaller brakes, differant engine and trany, weaker springs, smaller exhaust, smaller wheels & tires, smaller anti-roll bars, all the cosmetic differances and I'm pretty sure no power window etc... options. Doing swaps on parts between the NX 1600 & 2000 is not to hard.