The entire body of scriptures in Hinduism is divided into Śruti and Smṛti which means heard and remembered in Sanskrit respectively.
Sruthi denotes a category of texts that is divine in origin. They were traditionally transmitted orally by Brahmins and learned people which preserved the purity of the tradition. Because of it's divine origin, the importance is given to the preservation of the text in the original form by recitation with emphasis on intonation and preservation of its divine attributes. The Sruthis include the four Vedas and supplemented by Brahmanas, Aranyakas and Upanishads.
The Smritis are based on the teachings of the Vedas. The Smriti stands next in authority to the Sruti. Smrtis consist of non-Vedic literatures that portray the rules of dharma e.g. the Dharmasastras, Itihasas, and Puranas. There are eighteen main Smritis or Dharma Sastras.
There is a very engaging article on this by Sri Swami Sivananda, the founder of Divine Life Society.