An informative essay educates the reader on your topic. It doesn't include your opinion or persuade others to take a certain action or stance.
For example: Writing a history paper
An argumentative essay presents an argument from both sides of an issue.
For example: A pros and cons paper
A narrative essay has a single motif, or a central point, around which the whole narrative revolves. All incidents, happenings, and characters revolve around a single motif presented in the narrative.
For example: Senior portfolio autobiography