Answer 1

printf() prints the output(like string,integer,floating point etc) to the stdout i.e. screen.
whereas puts() prints only string to the stdout.

it is advisible to use puts() instead of printf() for printing string.
example - to print the string "Hello%World"

#include<stdio.h>
int main()
{
puts("Hello%World");//prints Hello%World
printf("Hello%%World");//prints Hello%World
return 0;
}
As you can see in case of printf() an extra % is inserted. To avoid all these extra work use puts() for printing strings.