[the_why_of_y]

Only superficially; the display server architecture was quite different and more powerful in NeWS:

https://news.ycombinator.com/item?id=22456575

There are a lot more interesting DonHopkins comments in this thread:

https://news.ycombinator.com/item?id=22455722

[pjmlp]

Sure, if you focus only in what Postscript was capable of, however many of the ideas were possible via the Objective-C Kits.

That is the part of NeXT that many miss, and it also has in common with SunOS/NeWS, the UNIX compatibility was only the bottom layer, the cool parts were above it.