The first feature - the structure. Thesis work structure is rigidly written and even putting into the form of a table of contents. In an essay, there is no formally rigid structure, of course, the essay has a certain logic of presentation - one of the first argument, then - on the other. There is no table of content, no dedicated chapters, sections and paragraphs. Instead of introduction and conclusion - a paragraph (or two paragraphs). Essay is free of relevance, formal goals, tasks and other things, strictly required in the introductions to the thesis works, graduation paper, etc.
Second feature - style. Thesis and coursework style should be scientifically educated, and in the graduation project - even desirable academic. In the essay, such rigidity is not required, though, of course, don’t paste jargon, slang words. Just a good competent speech. To become researcher in this case, is not necessary.
The third peculiarity - information saturation. In thesis, especially Thesis Project, it is just necessary to bring a lot of not very important, empty information - statistics, quotations from science guru and other data, that demonstrate that students are familiar with the literature on the topic. In an essay, even in an essay on economics or marketing, there are less desirable statistic and other wise quotations. That is, certain information, of course, is necessary - it reinforces the argument, but the scrupulous precision would not be required, so you can use just comparison information.
The fourth peculiarity - a reference list. Here, essay differs in principle from the thesis and graduation projects. In the essay, you can do without any references. Just your own thoughts!
The fifth feature - bibliography. References in the essay are normally not required. However, just in case, it is better to make this list - will not be worse.
Thus, the essay, on the one hand, is a kind of Thesis Project, and on the other - it's just an article from (or to) the magazine: essays on economics - an article from the Economic journal, an essay on the philosophy - an article from the Philosophy journal. Everything is simple!