How was the "American Renaissance" era in American Literature differnent from the "Discoveries and the Colonies" era in terms of types of literature?
Early American literature was comprised mostly of personal accounts and diaries related to making the journey to the American continent (from both the African-American and English perspective). Consider Olidah Equiano and William Bradford. During the Puritan Era, texts were religious based and focused on other-wordly concerns such as salvation. Because of strict Puritan doctrine, most literature of this period is didactic; you won't find much fiction or drama. Poetry was used (Anne Bradstreet and Edward Taylor) to explore the human being's relationship to God. By the time of the colonial era, most literature focused on independence and liberty. Genres included the essay and pamphlet.
Once independence was achived, American writers could focus on the development of a truly American literature. This really wasn't achieved until the period in question, The American Renaissance (which is really a misnomer, as it is literally a "birth" not a "re-birth"). This is the era of the short story (Irving and Poe) as well as the development of the philosophical and political essay (Emerson and Thoreau). The pinnacle of the era was the early 1850's which saw major achievements in American Literature: the birth of the American Novel (The Scarlet Letter and Moby Dick), the publication of Walden, and Whitman's Leaves of Grass.
So, the literature of the American Renaissance is much broader in scope and truly reflected unique American themes, something that early American literature struggled to do.