For Interface Transactions,INV_TXN_MANAGER_PUB.PROCESS_TRANSACTIONS DOES below things:
1)validate_group (Validate a group of MTI records in a batch together)
2)validate_lines(Validate each record of a batch in MTI)
3)tempinsert(insert records from MTI into MMTT)
4)calling inventory transaction Manager(insert records from MMTT into MMT)
For Pending Transactions,INV_TXN_MANAGER_PUB.PROCESS_TRANSACTIONS DOES below things:
calling inventory transaction Manager(insert records from MMTT into MMT)