Confirm BOD

When would we use the Confirm Message vs the Confirm BOD?
OpenAPI (POST)
JSON Schema
Sample Payload
{
  "confirmBod": {
    "releaseIdentifier": "10.7",
    "systemEnvironmentCode": "DEV",
    "applicationArea": {
      "sender": {
        "identifier": "MarySmallBusiness"
      },
      "receiver": {
        "identifier": "LargeCustomerA"
      },
      "creationDateTime": "2021-03-02T19:43:50.340Z",
      "scenarioIdentifier": "Order-to-Cash",
      "correlationIdentifier": "a57773f6-2666-4d67-b6aa-c4155c873aff",
      "bodIdentifier": "PurchaseOrder"
    },
    "dataArea": {
      "confirm": {
        "originalApplicationArea": {
          "sender": {
            "identifier": "LargeCustomerA"
          },
          "receiver": {
            "identifier": "MarySmallBusiness"
          },
          "creationDateTime": "2021-03-02T19:43:50.340Z",
          "scenarioIdentifier": "Order-to-Cash",
          "correlationIdentifier": "a57773f6-2666-4d67-b6aa-c4155c873aff",
          "bodIdentifier": "PurchaseOrder"
        }
      },
      "bod": {
        "actionCode": "POST",
        "bodIdentifier": "PurchaseOrder",
        "processingResultCode": "Success",
        "bodFailureMessage": {
          "errorProcessMessage": [
            {
              "typeCode": "NA",
              "identifier": {
                "content": "ORA-12320",
                "schemeIdentifier": "DB",
                "schemeAgencyIdentifier": "Oracle"
              },
              "description": "NA",
              "reasonCode": "NA"
            }
          ]
        }
      }
    }
  }
}