Whether or not you articulated it, you have probably known since before you first put any words on the page what type of article you were writing. This will make a difference where you can publish it. Certain types may be in more demand than others, or may be published in some journals but not others. (Check the submission guidelines of the journal you're interested in.)
1. The Original Research article is the first kind we usually think of. It's sometimes called a "study." The classic example is an experiment to test a hypothesis, and a report on the results. However, a wide variety of research methods in make Original Research articles the mainstay of all academic disciplines. They are where new knowledge is disseminated to fellow scholars. Original Research articles are easy to identify because they start with a Review that contextualizes the research, and then go on to discuss the Research Methods, what happened as they were carried out, Results, and finally a Discussion of the implications. Write an Original Research article when you have done research to create new knowledge.
2. The Review article looks at multiple Original Research articles by multiple authors on a certain topic, and creates a useful analysis or synthesis of them. A Literature Review provides an overview of what is known in a representative selection of the scholarly literature on a subject within whatever scope parameters are set by the author. Write a Literature Review when your goal is to help someone get up to speed in a very specific topic within your discipline, or know what has been discovered and discussed in that subtopic recently. A Systematic Review is much more time consuming and is rarely performed by only one author, because instead of providing an overview, it is trying to correct for biases and errors in the content being reviewed in order to answer a question or solve a problem. It requires an exhaustive list of sources to pull in, compare, and analyze as much of the content on that topic as humanly possible. Write a Systematic Review when you have enough time and the ability to perform an exhaustive search, and think you can resolve conflicting or unclear answers to the same question found in the literature. A Meta-analysis may start out with an exhaustive search for sources, but then cuts it back to include only sources that meet certain research method and measure of certainty criteria so that the sources can be reasonably compared. Then the researchers use statistical methods to combine the results from those studies into a meaningful synthesis. Write a meta-analysis only if you are knowledgeable in your discipline's research methods, skillful in statistics, and confident that you can perform an exhaustive search of the literature and then summarize what it all says when taken together.
3. The Case Study is a report on a specific case within the field experience of the researcher in many of the applied sciences and social sciences. Like an Original Research article, a Case Study shares new knowledge with the scholarly community. A Case Study begins with an introduction that contextualizes why this case is of interest and brings in any necessary background information. Then the specifics of the case are described with attention to detail and measurements. The researcher then discusses what they did - what intervention was performed - and then the outcome, again, with attention to detail and measurements. Finally there is a discussion section, where it is important to address which factors were likely due to the intervention, and which were likely not, as well as the implications of the findings. Write a Case Study if you have encountered something novel that reveals new insights or understandings in your subject area.
4. Perspectives, Opinions, and Commentary are not strictly speaking research articles, but essays from the point of view of a scholar who has some benefit of knowledge, experience, or insight to share.
5. A Theoretical Article is somewhere between a Review and an Opinion. It brings together existing knowledge the author's original theoretical framework or paradigm. Write a Theoretical Article if you have a breakthrough concept or framework that could help others understand your subject area in a new way.
There are some other less usual or discipline specific article types: