stdio.h와 cstdio의 차이

기능상의 차이는 없으나
C++에서
stdio.h는 global namespace를 사용하고
cstdio는 std라는 namespace를 사용한다.

standard library
Set of functions, constants and variables available also in C language. They are divided in different header files:
stdio.h, stdlib.h, string.h, time.h, math.h, ...
(available also with the names cstdio, cstdlib, cstring, ctime, cmath, with the only difference that if included thus their content is declared within the std namespace)

참고
http://www.cplusplus.com/ref/indexr.html