When a novel is using the first person point of view, the reader is getting the impression that he is a part of a story, he is completely immersed in it. First person narrators tend to be more subjective and closer to the reader in that they think about what the reader may think, and not just narrate the events. On the other had, third person narrators are completely different - they give off this vibe of distance, and they are quite objective, usually tending to just narrate what is going on around them.
Hope this helps!
