In India we have two categories of Scriptures - Shruti and Smriti. Shruti means heard. Heard from the Self within. It is the Lord speaking. It is the Universe speaking to us directly. When the body, mind and intellect are purified the source of existence Universal conciousness speaks through that body mind complex. This is called Shruti. This is what our Rishis did. Worked on the purification of self - becoming a vehicle for Univerals Conciousness. This became Shruti - Vedic literature. This is Revelation. From Higher Source to lower conciousness. Revelations are universal in nature. Sanatana. Coming from Universe, they are equally applicable to all.
On the other hand, there is individual effort to apply the principles of Universal Truths - Revealations to our day to day life. To our spiritual practices. To our society. This is the realization part. Realizing the revealations. This is the application part of revealation. There are smritis - like manu smriti etc. Smriti stands for memory. Memory comes from two components.
Memony from experineces in life - society, environment... Memory comes from listening to Shrutis, listening to revealed Truths. Synthesising these two leads to realization. While Shruti is
Universal in nature, Smriti is not. Smriti is time and space bound. It involves changes as the society changes.
While Shruti can be called as Universal first principles, Smriti can be called as second principles - applied principles. While Shruti can not be amended, Smirti can be amended depending on the time and location.