These are very very very old problems...
Providing reports on statistics depends on the definition of the Statistic, the definition of the Subject (Object), the aggregation rules for the volumes and the absolute timings for the period being reported.
Comparing statistics depends on the parameters which are set out, above. The more systems you have to compare, the more factors will need to be a part of your solution. Even the Genesys reporting components can conflict, depending on the parameters set on them!
Rather than go down the path of asking why they do not match, I would suggest that you decide on a level of tolerance between systems and stick to it. A good rule of thumb is to accept a variance of +/- 3% in the volumes.
This being the case, your 5 to 7 ratio is way outside a 3% tolerance, so I would suggest that you look at the defintions;
[b]
Objects [/b] - are the definitions of Agents the same in both systems? By definiton, is one reliant on a LOGIN or ACD Position, whilst the other measures a Persons' statistics? Could that Person have logged on to another ACD Position...?
[b]Stat Definitions [/b] - "Received Calls" seems a little generic. Do you mean Answered? Is the definition of the Stat the same for both systems?
[b]Aggregations[/b] - are both reports showing Daily, Hourly, etc. volumes or are they TOTALS being compared? Are you comparing Daily with Daily, Hourly with Hourly, etc. - or are they different aggregations?
[b]Time Periods[/b] - Is the time period the same? Where a time period begins or ends, how are "Received Calls" accounted for - is a call that ends in the period counted within that period or is it attributed to the previous period?
That should give you some food for thought...

Tony