Depends on what exactly you mean by resources and what kind of data is going into the columns. In general, VARCHAR is used for variable length strings. If your data is always going to be 50 characters long, use CHAR. If there will be large discrepancies in the length of strings that will be entered, consider using VARCHAR.
CHAR columns take up the designated amount of space for each record. VARCHAR columns only use the required amount of space + 1 extra byte. I believe that CHAR columns search faster, but VARCHARS take up less space (when used with variable length strings) and thus cut down on table size, which also keeps searches fast. For 50 characters, I don't think it would make much of a difference. If your entries are all going to be 50 characters, use CHAR, but for variable length strings, it is more logical to use VARCHAR.
-- will always hold 50 characters (pads shorter with whitespace.)
-- will always use 50 bytes
-- will hold up to 50 characters (no padding shorter strings.)
-- will use string length + 1 bytes