For starters, soft pine is almost never used for dimension lumber--2X4, 2X6 etc., accept in the south east, where it will nearly always be "yellow pine."
Dimension lumber is nearly always spruce in the northeastern U.S. and Douglas fir or Sitka spruce in the west. If it comes from Canada, it is probably spruce. If Oregon, D. fir or spruce, though it could be one of the true firs, such as noble fir or white fir.
Pine in any shape ususaly has wider growth rings and it is softer than spruce. Press a thumbnail into pine and you will make a mark.
If you talk to a store manager, they would be ABLE to tell you where the shipment came from. Whether they would take the trouble to look it up, is another thing altogether.
Jim Davis