From : "... one can imagine at least three different styles of essays, including biographical, introspective, and inspirational. essays tend to be a chronological description of relevant life experiences, but such essays often lack flair or distinction. essays can be especially revealing, but may be very difficult to write or relate to practical aspects of medicine. The essays usually entail some sort of "I want to save the world" and should be avoided unless you can cite convincing evidence that you actually have saved the world (several times). " (emphasis added)
Academic essays can be written in a wide variety of styles
However it may be referred to, a thesis is certainly an important essay that requires a considerable amount of work and understanding. Generally, a thesis will be very much a research-based piece of work. Unlike some lesser styles of essays, a thesis will often be a unique paper that is based on an original idea. Even if the idea or topic is not original in itself, the concepts and themes that are discussed within it may well be, thus taking a fresh approach to a pre-existing topic. Therefore, it requires a considerable amount of research and understanding in order to be written as effectively as possible.
Essays can be descriptive, persuasive or narrative
"At this point we have discussed and constructed two styles of essays: Research and Expository; however, the same format was used for both essays. There are many other styles of essays. The format presented in this course can be used for all styles of essays. Remember: the format is the technique of an essay; the style is the purpose of an essay."
Guide to Different Kinds of Essay - Gallaudet University