Receipts Transaction History in iProcurement

Hello,

Could someone help us to understand (1) why the Receipts Transaction History in iProcurement contains so many more lines than the Receipt Transaction Summary in the Core receiving form and (2) why they don't necessarily correspond to each other?  In the screen shots, below, receipt 313660 in iProcurement has four Receive Items transactions and four Return to Supplier transactions:

In the Receipt Transaction Summary, the same receipt - 313660 - has one Receive transaction, one Deliver transaction, one Return to Receiving transaction, and one Return to Supplier transaction:

Why do the transactions in iProcurement not appear to correspond with those in the Core receiving form?