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 .