It's highly unlikely that you'll ever pen a best-selling essay, but you may certainly be the next best-selling author of a novel. Whether your essays and your novels will be at all similar to one another depends only on which type of essay and which type of novels you choose to write.
The purpose of an essay is to inform readers. Writing an essay means researching relevant information in order to understand the topic and be able to form an opinion or offer thoughts about it. Essays also require that you organize your thoughts, usually through some sort of written outline, and state the point of your essay in a thesis statement.
The purpose of a novel is to entertain readers through story-telling, although some very entertaining novels are also informative. Authors of novels use some of the same techniques that can be used for an essay, such as descriptive writing and using personal narratives to make a point. However, a writer penning a novel also has to consider elements like character and plot development, which makes writing a novel quite different from writing an essay.
The average essay is five to seven paragraphs long, which includes an introductory paragraph, three or more body paragraphs, and a conclusion paragraph. Each paragraph should relate back to the thesis statement in the introduction by having topic sentences that expand on the writer's main idea. Essays are very focused pieces of writing that do not stray from the original main point into other subjects.
Novels vary widely in length. Some graphic novels are only 50 pages long, while Madison Cooper's Sironia, Texas is over a million words, or around 1,731 pages long. While novels generally focus on an overarching story theme, writers can explore many different ideas and topics within one novel.
There are four basic types of essay: persuasive (arguing a point and trying to convince readers to agree), descriptive (describing an object or scene by painting a picture with words), expository (recounting facts in an organized way), and narrative (telling a story that makes a point). Like writing a novel, a narrative essay is story-telling, although the story will be much shorter and more focused in a narrative essay.
Novels come in many different types, such as fiction, non-fiction, romance, and history. Novels can be epic, like J.R.R. Tolkien's Lord of the Rings, or just for fun, like Stephanie Meyer's Twilight.