When you programmatically create a new sales order in dynamic mode, all of the same sourcing behaviors that occur in the UI also occur in your script as each line is executed. You can obtain sourced, validated, and calculated field values in real-time without first having to submit the record.

When working with records in standard mode, you must submit and then load the record to obtain these same values. In standard mode, all business logic is executed only after the data is submitted.