I guess the main difference people are noting is that obsessions are narrower – in scope of the topic, or (geographic) space, or in time. A crime beat is a broad category. Obsessively following every detail of a particular crime for a while until it’s solved (or there is nothing more to say), is an obsession. Once the story is over, obsession is closed, and the reporter moves to a new topic.
But another way the difference is explained is that an obsession is actually broader, not narrower, by being multidisciplinary. Instead of looking at many stories from one angle, it focuses on a single story from many angles. This may be a way to solve some Wicked Problems. So, looking at the Big Picture of crime, e.g., causes of crime and what measures potentially reduce crime in various parts of the globe, cultures, past eras, etc, from every angle possible, is also an obsession.
From here.
The idea of “obsessions” as journalistic beats is, in itself, becoming an obsession for me. The idea of following an idea and continually coming back and coming back and coming back to it, exhausting it, is one that I – ironically? – keep coming back to. It’s in my head recently because I have been criticized by editors lately for doing that very thing too much, and I’m not sure whether to apologize or argue the case for doing so…