How would the story be different if Joyce had not used the participant narrator in writing "Araby"?
"Araby" is a poignant initiation story told from the first-person point of view by the boy who experiences the events. It is an example of what might be called an interior plot--the heart of the story lies in the boy's thoughts and emotions rather than in the series of external events. For example, the external events are very simple: He watches Mangan's sister, he tells her he will buy a souvenir for her at the bazaar; he manages to get to Araby, but arrives late. It is instead his emotional journey, ending in disillusionment and despair, that drives the narrative and develops its theme.
Joyce could have examined the boy's feelings by writing the story in the third-person omniscient point of view, but it would not have been as effective. No point of view brings the reader closer to a character than the first-person point of view, and the power of "Araby" is developed through the reader's understanding of this boy's deepest needs and desires. To really understand his environment and his feelings, the reader must experience them as he does, and that is best achieved by listening to him tell his own story.