sizeof: calculates size in bytes of: variable, functions, arrays... depends on it's type and value.

your two functions is similar but in one is "unsigned" and in the other is just "char", difference in that is "unsigned" means values is only >= 0; it's dont make variables larger or smaller in size.

this is how much size in language C, of "unsigned char" and "char":

char : one symbol. Have 1 bytes (8 bit).

unsigned char : one symbol. Have 1 bytes (8 bit). Any value from 0 to 255

If you have other question or if i need to add something ask in comments!