Reports have headings - it makes reading any article easier as you can place one set of arguments or information under one header. Structure is introduction -> sets of arguments and points -> conclusion under a unique header. It is a presentation focused document meant for a specific audience.
Essays are heavy! No graphics is used so you will rely heavily on using examples etc to emphasise your argument. Like a report it should flow from introduction to conclusion. You're using words to persuade the audience to agree with you and it should always have a concrete conclusion.