Quran is the divine book of law which declares the commands and prohibitions of Islam. However, sunnah is the practice of these laws by Prophet Muhammad (pbuh).
Quran is the last divine book which was revealed through Gabriel (as) to Prophet Muhammad (pbuh) from Allah (swt) and which comprises the principles of happiness for the whole humankind. Quran declares laws for the order and the happiness of both religious and worldly life. It states why the universe has been created, what the duties of the creatures are and what the amazing arts and the adornments of this world mean; in other words, the purpose of life, creation and the universe. Quran saves humankind from randomness and anarchy by informing him of his unique value and his real purpose and significance. It provides prosperity, peace and order of both personal and social life through worship, belief and a faithful perspective.
Sunnah denotes the sayings, actions, approvals and attributes of Prophet Muhammad (pbuh). They are the Islamic commands which have so many earthly and spiritual virtues for Muslims who adhere, a great deal of rewards for those who practice and plenty of loss for those who abandon.
Sunnah is the second Islamic source after Quran.