If there is one thing I have picked up over the years with Genesys Solutions it's; never compare different reporting elements...

I have spent way too long, on behalf of many different customer areas, comparing and defining exactly what a report shows, how it is composed, what changes have been applied to it, where it differs from other reporting engines, etc.
WfM counts non-recurrent interactions (if you have DCID "ticked'), CCA counts volume, Infomart count interactions/legs... it really does depend on what a business want the reports for, as opposed to spending all of the time justifying the details of the composition of the stats in the results.
The world would be a simpler place if, like the industry standard definition of "SLA", we all stuck to the same definitions for reporting - wouldn't it...? Unfortunately, there are usually too many "business variables" (such as "he was off sick that day, so it doesn't count - can we find a way of excluding those figures...?") to see what really happens in reporting.
A good way might be to start fresh - wipe the slate clean and go for new reports with statistical definitions that cannot be amended - and then let everyone use the same ones, instead of repeating the exercise with every variation to cater for every eventuality.
Just my thoughts, really...

Tony