Difference between Aggregation types in the bw4hana request and sap sac

Hi,

Why we migh have difference in the aggregation type between sap bw4hana and sap sac

for example in the first picture ( SAP BW4HANA ) the result of fixed quantity is calculated as the max and for the volume is calculated as the sum

But in the sap sac model i got the opposite

thanks,