What is the difference between inline assembly call and direct call?

Question

What is the difference between using thet= __rdtsc() function directly and using

 asm __volatile__ (
       "rdtsc               \n"
       : "=a" (t));   

I have seen on stackoverflow that many people do not recommend using inline assembly, but then I have seen that the source code of many top conferences uses inline assembly. Is there any difference between them?