Why do Inventory Adjustments on QuickBooks sometimes differ on AdvancePro?

QuickBooks is a stand alone software where its stock may be impacted by different sources, cases, scenarios which are outside of AdvancePro. For this reason we have two methods how AdvancePro can export inventory to QuickBooks.  First is match ("level") AdvancePro and QuickBooks inventory on export.  Second is export exact Adjustments made in AdvancePro.   

When first method is used, "Automatically adjust QuickBooks Inventory when manual Adjustments are made in AdvancePro", AdvancePro will send the final stock to QuickBooks and export will compare it.  If there is a difference a quantity adjustment will be posted for that difference.  In this case adjustments in QuickBooks may not match adjustments in AdvancePro but at the end of the day its final stock will match AdvancePro (considering there are no pending transactions which are also taken into account during export.  For instance, pending invoices would be added (+) to exporting qty and pending Bills would be deducted(-) , etc)
When second method is used, "export exact Adjustments made in AdvancePro", AdvancePro will send exact quantity adjustments that you have performed in AdvancePro.  As a result, you will always be able to match the adjustment made to inventory in both software.  However, the final inventory quantity may differ.