Is relaying a piece of news or narrating a situation considered backbiting, and how can one differentiate between the two?

Relaying information about a person or a situation they experienced is not forbidden backbiting unless they dislike it. Backbiting is "your mentioning of your brother that which he dislikes." So, if what is said about him is true, then you have backbitten him; and if it is not in him, then you have slandered him.