It depends. String center to string center. Probably you are right. But String edge to string edge... the calibrated ruler doesn't lie.
That doesn't really take into effect the tapered strings. Which both basses have so I ruled that out as a variable.
And regardless the number... as you can see from the second photo... whatever it is... the NS-2 has less space between the strings than the bolt-on.
And to me, this changes the feel of the neck. Not a bad thing. Just something I happened to make a mental note of when playing them... like "I need to check that... it feels wider" and sure enough. The measurements proved my "feel" for the neck right.
Looking at them side-by-side you can clearly see the spacing difference... it's visible with the eye... no ruler needed really.
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Side by Side Comparison
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This image shows the string spacing of the NS-2 as compared to the NS-2J SE bolt-on... the calipers are set to the measurement of the NS-2 at the same location. Clearly the NS-2's string placement is "tighter" or "closer"
1. String spacing, when side to side/edge to edge, is never measured at the tapered (if so equiped) area of the string.
2. You clearly have two different bridges there.
3. Spector's site clearly lists the NS2 as .75" spacing at the bridge. This roughly translates to 19mm, which is standard 4 string spacing (and many 5 and 6's) on most manufacturer's basses. 17mm is what many (if not most, including Spector) manufacturers set for spacing on their 5 and 6 string basses.
4. Visually the E (where you measured) on that NS2 is clearly not dead center on that saddle and is set inwards, unlike the other 3 strings. In fact, it visually looks like the E & A are closer than the others because of this.
Actually, if you had measured the bolt-on between the G & D or D & A you'd be waaay off as the D string is spaced way inside compared to the other 3 (Look at the saddle. Wasn't set up properly).
Now what may be going on on this new NS2, bolt on variation with the different neck and bridge I can't speak to.
But unless something has unknowingly changed, NS2's are still considered .75"/19mm spacing as they have always been.
EDIT: FWIW, I'm not sure if this NS2H is using the same Hipshot bridge, but the NS4H's Hipshot bridge (4 string) is also listed at .75" (19mm). It would seem visually that the whole discrepency is due to that NS2's E saddle being grooved improperly.
This isn't surprising as I've had to re-groove or flip around 180 degrees several of the Spector saddles (both US and Euro) over the years to make the string spacing properly equal.