The Difference between the Sunnah and the Quran
The Quran is the foundation of Islamic Law. It is the miraculous speech of God that was revealed to the Messenger, may the mercy and blessings of God be upon him, by way of the angel Gabriel. It has been transmitted to us with so many chains of authority that its historical authenticity is unquestionable. It is written down in its own volume, and its recitation is a form of worship.
As for the Sunnah, it is everything besides the Quran that came from God’s Messenger. It explains and provides details for the laws found in the Quran. It also provides examples of the practical application of these laws. It is also either direct revelation from God, or decisions of the Messenger that were then confirmed by revelation. Therefore, the source of all the Sunnah is revelation.
The Quran is the revelation that is formally recited as an act of worship, and the Sunnah is revelation that is not formally recited. The Sunnah, though, is just like the Quran in that it is revelation that must be followed and adhered to.
The Quran takes precedence over the Sunnah in two ways. For one thing, the Quran consists of the exact words of God, miraculous in nature, down to the last verse. The Sunnah, however, is not necessarily the exact words of God, but rather their meanings as explained by the Prophet.
The Quran is true word of God and no doubt about it, if you doubt you are by definition non-Muslim. When the prophet says things that not agreeable to God or actions he clearly correct that to him and publicly through his Quran. For things God did not correct to him it is either inspiration to him through visions or inspirations through finding the words in his mind (Christians call it the holy spirit) or self wisdom that God allowed him to talk it and trust him to do that since he give us the wisdom as mentioned in the Quran. "that who got the wisdom got a lot of goodness". There are very clear words of Sunna like some of the sayings of the prophet as the holy Ahdaith which are directly words from God but in the prophet own words and not like the Quran it is like the Hadith God says whoever comes to him walking he comes to him running-------
Shia on the other hand had words from people described from Muhammad (PBUH) family and some of their scholars that they consider it very accurate and a revelation or close enough. Mulims Sunni are more or less think the way like the scintific way of thinking "evidences". The Quran clearly mention that the true revleation is the Quran that we need to follow and the Sunna. In Quran God warned us to be sects and go astray like we are doing now. The prophet said "I left for you what if you hold on you will never go astray the book of God the Qruan and my Sunna".