That looks like a chestnut. See the reddish nape triangle, the beginnings of ticking, and the agouti markings:
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This kit is old enough to have begun to develop ticking on its forehead, sides and legs, but even as a newborn you could tell it's not a black because of those light inner ears. (The photo of the black, in your second post, shows the dark, solid-color inner ears, rather than the lighter colored ear lining of an agouti or otter). Otter would not have that ticking on the forehead.
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Chestnuts can vary pretty dramatically in the amount and intensity of the orange/red tones. But otters will not have any ticking on the head or back: they are more like a self on top, and an agouti on the bottom. 
NZs can be any color, although in the US they're only accepted for show in white, red, blue, black, or broken versions of those colors. Even if there's not been a crossbreeding event in many generations, NZs, especially whites, can carry all kinds of hidden surprises, which will materialize if they're bred to a self (black or blue) or an agouti (red).
