Difference CHAR(1) and VARCHAR2(1)

Hi
Can some one tell me the major difference between CHAR(1) and VARCHAR2(1), I need to use flag column of 1 byte.

Which is best for use, and why, index will also apply for this column.

Thanks & Regards
Anuj

use any of it.. dosent really matter in this case..

CHAR(10) allocates 10 space and if you use only 3, say for example 'SAM', then balance 7 is left as such, won't be used or reusable. But if using VARCHAR(10), 'SAM' will take 3 and rest 7 will be reused. But in this case of FLAG, nothing make much difference, anyhow it is only 1 character