To clarify what I stated earlier, I contacted the Canadian distributor ... Aurifil changed their plant locations a few years ago, from Italy to Italy!
With that change, some of the variegateds did change colours/hues/tones, but the plains pretty much stayed the same.
To identify the difference production locations, looking at the labels on the spools, smaller print was used at the older plant, and thus larger for thread made at the new plant. Without two spools in front of you it is hard to know that difference, but those of us with a thread stash may find some of both!
If you have a colour chart dated 2015, it is representative of the new plant and any of the changed colours.
As for colour numbers and dye lots, please see post #4.
Hope this helps.