New vs NIB vs Unfired
We have a store in town that differentiates New/NIB/Unfired.
I found a Ruger MkII stainless bull-barrel that looked good. Tag said "UNFIRED" so I asked what they meant. In this case, it meant, "actually new, bought by someone and stored, original box & accessories lost."
We tore it down right there. If that thing had ever been fired beyond factory testing, someone had cleaned it with perfect tools and solvents, restored the factory finish to all the little bits, and reassembled it without leaving any discoloration to any surface usually exposed to heat/combustion.
When I told the wife I'd found her new MkII, I told her it was NEW, never been kissed. Told her the box had been lost. She said, "as long as it's new, I don't care." Neither did I. Bought it on the spot. Hard to find a Mark II with no miles on it.
Their "NIB" designation means "complete, as shipped from the factory, with all accessories and manual, and unfired."
Their designation of "NEW" indicates that it's never been sold retail. May have box. May have manual and/or accessories. In one case, they had everything EXCEPT the flipping box. Box had gotten lost in an inventory screw-up.
In my world, all three of those designations mean "virgin gun -- never been kissed."
They also have a category "LIKE NEW" or "AS NEW" to designate something known to have only a box or two of traffic. They've got a lovely 686+ with a 2.5 or 3-inch barrel that they sold, got it back the following week after one box of ammo, traded for a larger (.44 mag) piece. Fifty rounds only. Tagged "LIKE NEW" and has original box, accessories.
Of course, this store isn't online, it's strictly brick-n-mortar and face-to-face so I get to kick the tires when there's any doubt.
I'd need serious recommendations before I'd trust the labeling of an online outfit.