Difference between NULL and NUL

NULL is a macro defined in for the null pointer.

NUL is the name of the first character in the ASCII character set. It corresponds to a zero value. There?s no standard macro NUL in C, but some people like to define it.

The digit 0 corresponds to a value of 80, decimal. Dont confuse the digit 0 with the value of ?? (NUL)!
NULL can be defined as ((void*)0), NUL as ??.

basically NULL points the predefined value zero to the compiler !!

and NUL is the name of 1st character in the ASCII character set!!