NF is lighter, smaller, illum is brighter, has .5 mil subtended reticle, locking diopter, extra 2x, FFP, easier to turn zoom ring (i.e. does not need anything more than the factory PTL).
Vortex is heavier, better eye box, brighter image, flatter image, non-locking diopter, really needs a throw lever.
Despite the brighter illum on the NX8, I find the Razor better to use for speed on 1x. It's still heavy for what it is, and I find the zoom ring stiffness and thick upper half of the reticle irritating. The NX8 is image is decent until you start moving higher than 6x, at which point the brightness goes and the eyebox tightens dramatically.
Depends on what you want. NX8 has some compromises but does a lot of things well enough.