When you select a column value into a CHAR variable, if the value is shorter than the declared length of the variable, PL/SQL blank-pads the value to the declared length. As a result, information about trailing blanks is lost. If the character value is longer than the declared length of the CHAR variable, PL/SQL aborts the assignment and raises the predefined exception VALUE_ERROR.
When you select a column value into a VARCHAR2 variable, if the value is shorter than the declared length of the variable, PL/SQL neither blank-pads the value nor strips trailing blanks. Character values are stored intact, so no information is lost. For example, when you select a blank-padded CHAR column value into a VARCHAR2 variable, the trailing blanks are not stripped. If the character value is longer than the declared length of the VARCHAR2 variable, PL/SQL aborts the assignment and raises VALUE_ERROR.
The same rules apply when fetching.