MRTG only uses inOctets and outOctets, while the ASHostMatrix and DetailHostMatrix have more information broken
down. The differences should be negligable. The comparison between MRTG that uses SNMP and NetFlow is not a valid test. The reason is NetFlow reports only L3 flows while the interface statistics reports total traffic. Netflow derived data to be 10 to 30% less than that from MRTG - SNMP. also Netflow accountin is more based on packet flows that byte counts.