Difference in complex and simple calculation

Why does the graph change like this between simple and complex computation model i tried the same calculation in winisd and it seems to be closer to the simple version. 

Red=complex

Green=simple

The simple model uses a small number of the parameters like FS, VAS, QTS to do calculations the wide number of speakers have such parameters in their tech docs. This is easier to use especially for starters.

And the complex model uses a different set of the parameters like MMS, CMS, RMS, BL, SD, RE, and so on to do calculations. Fewer speakers have that set of parameters. The calculations are more complicated but consider port and box behavior and therefore much more accurate.