Output difference in gcc and turbo C

Why is there a difference in the output produced when the code is compiled using the two compilers gcc and turbo c.

#include <stdio.h>

int main()
{    
    char *p = "I am a string";
    char *q = "I am a string";

    if(p==q)
    {
        printf("Optimized");
    }
    else{
        printf("Change your compiler");
    }
    return 0;
}

I get "Optimized" on gcc and "Change your compiler" on turbo c. Why?