Both the qur’an and the sunnah have guided muslims’ behavior for centuries. apart from discussing different topics, how do these two differ?

1.Qur'an is fixed and its the same for all of the copies and the narrating ..
unlike the sunnah where there might be a difference because of the narrating : you might find difference in some words depending upon the person narrate the hadith but in general they all lead to the same meaning although they use slight different words .

2.  sunnah is always emphasizing and explaining what is written in the Quran .

3. sunnah sometime include the actions , reactions and behavior of the prophet .

this is what I know , hope it helps .