These are the intellectual section of the Hindu writings, while the first four are intuitional.
And the fifth inspirational and emotional. Darsanas are schools of philosophy based on the Vedas. The Agamas are theological. The Darsana literature is philosophical. The Darsanas are meant for the erudite scholars who are endowed with acute acumen, good understanding, power of reasoning and subtle intellect. The Itihasa, Puranas and Agamas are meant for the masses. The Darsanas appeal to the intellect, while the Itihasas, Puranas, etc., appeal to the heart.
Philosophy has six divisions (Shad-darsana). The six Darsanas or ways of seeing things, are usually called the six systems or six different schools of thought. The six schools of philosophy are the six instruments of true teaching or the six demonstrations of Truth. Each school has developed, systematized and correlated the various parts of the Veda in its own way. Each system has its Sutrakara, i.e., the one great Rishi who systematized the doctrines of the school and put them in short aphorisms or Sutras
The Sutras are terse and laconic. The Rishis have condensed their thoughts in the aphorisms. It is very difficult to understand them without the help of commentaries by great sages or Rishis. Hence, there arose many commentators or Bhashyakaras. There are glosses, notes and, later, commentaries on the original commentaries.