The answer to this question is considered point of view. As the term suggests, point of view is the perch the writer provides for the reader to see into the heart of the story. If someone is in a car crash, you could tell the story from the point of the view of the poor crash victim, her distraught mother, her boyfriend, the doctor in the emergency room, the medical student on call – each one would have a different perspective or point of view, on the story. The narrator or teller of the story may stand within the story or outside it, narrating as it occurs, shortly after, or much later, providing in each instance a different narrative perspective in space and time. The reader sees the story through a narrative perspective close to the events or removed from them by various kinds and degrees of distance, examining, as it were, with a microscope, binoculars or telescope.
First Person Narration: from inside the story. The author creates a persona or mask through which the authors tells the story. In Huckleberry Finn, Mark Twain adopts the persona of Huck, who narrates the story. The author is bound by the conditions of the persona (frame of mind, education, attitudes etc) presenting only knowledge available to this persona, within the limits of the persona’s understanding, and expressed in terms appropriate to the persona’s personality and vocabulary.First person narration typically takes the form of journals, diary entries or letters.
Third Person Narration: from outside the story. The omniscient narrator is a god-like informing intelligence to everyone in the story at all times. This approach sends the reader further above the story’s events and characters than any other form of narration.