Of course Varchar2 is there to maintain variable length of columns. It keeps an internal pointer to maintain Variable length that means it wastes two bytes to keep first and last index where column starts and Calculates for each DML operation against that column. So We can Avoid this house keeping work using Char data type if we can estimate the maximum length of the column. So both have it's own significance. Be careful while using varchar2 (It make overhead for each row). Use Char if you are sure with the lump sum length of the column..
4 
1