labyrinthine in the sense that it's hard to get your bearings in a given track. there's always a lot happening at once, but almost no large scale changes, so you're constantly hearing something and thinking, "wait, has that always been like that?" the way the music resists being mentally mapped out makes it more mysterious and immersive. (and "trippy" if i can use that word.)
voodoo ray has that too, but it's not quite as "advanced" as newbuild in that respect.
of course the appeal of this approach is another matter...
and yeah, "harder" in the sense that it's not so much pretty as "mental" and high intensity, as barty pointed out. more of a harsh, eerie sci fi atmosphere as well.
Dunno about all that really, for me the thing with voodoo ray is that birds voice