There are three main types of essays in the English language:
For and against an essay.
The name of this type speaks for itself: in it you have to give arguments "for and against" on a given topic.
The writing plan: in the introduction, you introduce the reader to the problem; in the main body, you describe the arguments "for and against" in a neutral way, without expressing your own opinion; in the conclusion, you give your opinion on the problem and draw a conclusion about .
Unlike the pros and cons, an opinion essay is designed to express your thought on a topic. The peculiarity of an opinion essay is that you not only need to express your own opinion on an issue, but you need to reflect other points of view in the essay. So to speak, to look at the topic from different angles.
The writing plan: in the introduction you state the topic of reasoning; in the main part you express your opinion on the problem, backing it up with confident arguments, and also, describe what other points of view there are; in the conclusion you summarize, which reinforce the opinion you have expressed on the problem.
Suggesting solutions to a problem essay
Usually in such essays you are given some global problem, and your task is to suggest the most possible and relevant ways to solve it.
The writing plan: the introduction describes the problem and its causes; in the main part you need to offer several options for solving the described problem and the possible consequences of each of them; in the conclusion you summarize the results and the final solution or recommendations.
Usually, the type of essay depends on the chosen topic and is often stated directly in the assignment. If there are no recommendations on the type, then use any type that, in your opinion, best fits the given topic.
The above-mentioned types of English essays are the most common, but there are others. Sometimes you need to write about your achievements and plans for the future (for example, when applying to university or college), and sometimes you need a free-form essay about what's bothering you right now (that is, without a given topic).
Whatever the topic, it's a good idea to follow a certain common structure when writing your essay.