5.4L with 1.8L supercharger with 6250RPM redline vs 5.8L with 2.3L supercharger with 7000 RPM redline. A lot changed between 12-13.
I see identical curves, down to the lumpiness around 200 period. Which is more due to the large jump in period values at that point. The 13-14's just have a few points removed, 1.22, 2.17 and 3.64, to extend the curve below 100 period to achieve higher airflows.
I believe on a flow bench you put in fixed known airflow values, so those don't need to change, and you record the MAF frequency/ period from them. They certainly got slightly different values for period, but not an extreme difference and more so at the low airflow values. Maybe a different flow bench calibrated slightly better, hopefully.
11 vs 14.PNG
With those differing points removed so the same X and Y values are only shown.
11 vs 14 three points removed.PNG