The following code would include:

SELECT C$.$CUstID, C$.$CustName, O$.$OrderID

FROM Customer C LEFT JOIN Order O

ON C$.$CUstID $=$ O$.$CustID;

All rows of the Customer Table regardless of matches with the Order Table.

Only rows that don't match both Customer and Order Tables.

All rows of the Order Table regardless of matches with the Customer Table.

Only rows that match both customer and Order Tables.