A report is a presentation and analysis of findings and data from practical research, aimed at investigating, exploring and sharing specific information. Meanwhile, an essay seeks to answer a question based on research too, but through the writer's own point of view, to support his own conclusions.
Taking this into account, we may say that <em>annoying people on cell phones</em> is a topic more suitable for an essay.
When you compare two texts, you do more than find what is similar or different. You should also draw conclusions about how the techniques the authors use accomplish their purposes.
