Hi,
Entry date: Date of posting document in SAP.
Posting date: The date on which it should impact the financials, it can be different from entry date and can be from past also.
Note: Posting is manually selected by the user, while entry date is automatically picked by system as per the system date.
While defining the payment term, we need to select the baseline date, which means the date from where the credit period will start.
So if Entry date is selected there then credit limit will start from entry date, it wont consider posting date or document for calculation.
Hope this clears your doubt.
Regards,
Gunjan