Being a candidate preparing for IAS, you have to prepare for General Studies- for preliminary exam, mains exam and even for the interview. You must have noticed that few topics (that are given for essays in the essay paper) can be put under the category of general studies. They are directly related to sociology, politics, economics or science and technology. It is natural to have a question in mind- "if essays' topics are related to general studies, then, why is there a separate exam for it?" You will find the answer here itself and I also understand why knowing this answer is so important for you.
There are two things- knowledge and understanding. If you understand the difference in these two, then, you also understand the difference in general studies and essay. A person who has done M.Sc. in agriculture has agriculture related knowledge; however, an illiterate farmer has an understanding of farming. Both are related to agriculture, but, one has theoretical knowledge and the other has empirical knowledge. The person who has knowledge will have to develop it into understanding by doing farming for a few days. You can alsolook at it this way that there are many roadside mechanics repairing cars and scooters in small towns, but they wouldn't even know how to spell Mechanical Engineering. Despite this, they have sufficient knowledge to mend your vehicle. They do this on the basis of their understanding and not theoretical. knowledge. So, an essay is meant for a farmer if it is written about farming. And if it is being written on Electrical Engineering, then it should be for that 'chhotu' who keep busy all the day checking and repairing vehicles in a roadside workshop.
When we study a subject in general we are totally confined to that subject only. This is true for an essay as well. But essay is different in the manner that it can have many subtopics included in it. When you have to make someone knowledgeable of the topic, you cannot digress from the topic. However, if you want to make somebody understand, you can go to any extent, can give any example to make the concept clear. When a political science professor talks about the basic rights, then, he sticks to that and does not digress. However, when the same person becomes a minister and works hard for the protection of the basic rights of the people and addresses them, then, the facts and the points change. That means knowledge is obtained in the classroom, but, it is applied in the free ground of life.
Hence, it is clear that there is enough scope for analysis in General Studies. You can put forward your point using arguments. However, essays are never analytical. They are informative. You collect the information on the basis of which you come to your decision.
That is why you should be careful and focus on the point that you don't end up writing a General Studies paper instead of an essay. This thin line between these two should be very clear in your mind. If you are able to maintain this psychological.discipline, then, you would see that you can transform your knowledge into understanding and can write an effective essay. This will help you become a successful communicator.
I am definitely not saying that there is no relation between General Studies and essay. It is just not possible. There is a definite relation. An essay challenges you to show your talent while understanding this difference. I think my saying, 'your general knowledge is tested in general studies, whereas, the general understanding is tested in an essay', can make this difference clearer.