Four books are four different books. They may be fiction (stories or adventures) or nonfiction (information or facts). Five Classics are five books that are considered to be the best of a certain genre, or are especially important or influential in literature or history. They are usually very old books that have stood the test of time. Examples of five classics would be Plato's "The Republic", Homer's "The Odyssey", Shakespeare's "Romeo and Juliet", Mark Twain's "The Adventures of Huckleberry Finn", and the Bible.