Can someone help clarify my question about MAF changes for me?

Ive logged average MAF airflow (g/s) vs RPM as well as CALC.SELEBEN vs RPM. My logged average MAF aiflow g/s is considerably different than my calculated MAF table after factoring in my CALC.SELEBEN. Ive eliminated TP% changes and temps below 178* on both by way of the map filters.

What is the main difference in what Im looking at?

Why are the 2 different?

Im just trying to get a better understanding for each.