Narrative paragraphs have similar features of flow (or unity) and coherence. However, the development might be more related to the action or events narrated in the paragraph than to supporting an argument. Coherence in a narrative paragraph usually comes from the chronological order of the "story" or narrative. Similarly, a descriptive paragraph might find its development through giving a series of sensory details or of abstract ideas that describe an object (or concept or theory), rather than through support. These two types of paragraph - narrative and descriptive - differ only slightly in these respects from expository paragraphs, but the differences are still important.
Example: Imagine that you want to write a descriptive essay about your grandfather. You've chosen to write about your grandfather's physical appearance and the way that he interacts with people. However, rather than providing a general description of these aspects, you want to convey your admiration for his strength and kindness. This is your reason for writing the descriptive essay. To achieve this, you might focus one of your paragraphs on describing the roughness of his hands, roughness resulting from the labor of his work throughout his life, but you might also describe how he would hold your hands so gently with his rough hands when having a conversation with you or when taking a walk.