Ever had to reconcile intercompany loan accounts? They never seem to agree all by themselves do they?
I would export them both to Excel then carefully eliminate those transactions that occured in both, constantly watching that the bottom line difference did not change.
Then I would end up with transactions in each that did not have corresponding transactions in the other.
It was a slow and arduous job.
Once I got that far I would check each and resolve the mismatch.

Now? Download both to Excel, drop them into AI and say “List the transactions that cause the error”.
Moments later you have the list that took ages to build before.