Comprehensive and Detailed Explanation From SAP S/4HANA Cloud Public Edition, Management Accounting documents:

When a transaction is posted in SAP S/4HANA Cloud, the system identifies the nature of the CO (Controlling) object assignment

If you post a goods issue directly to a profitability segment, it is treated as a true account assignment49. In this context, the profitability segment is determined immediately by the underlying sales order or business process and is recorded directly in the General Ledger50. This "true" assignment allows the segment to act as a primary cost collector that can then be used in subsequent management accounting activities, such as allocations or multi-dimensional profitability reporting51. Statistical assignments (Option B) are for information only and do not allow for follow-on CO activities, while attributed assignments (Option D) are derived for reporting purposes from other true objects like cost centers, rather than being the primary posting target themselves52.