True crime is not far off from crime documentary. If anything I could see people arguing they're the same and it would really just come down to semantics.

To me, a " crime documentary" is a show or episode covering a specific crime or suspect. A True Crime podcast (or show, vlog, etc.) tends to cover a new crime or suspect each episode.

If anything, I would argue True Crime shows are a series of mini-documentaries so-to-speak.

Another thing to consider would be production value. When I hear "Documentary" I think of something I would see on TV or a streaming service. In other words I think of something backed by money.

When I hear "True Crime" I think of podcasts or vloggers. Typically a person or small group of people doing their own research and producing their own content.

A True crime podcast I'd recommend would be Small Town Murder. My wife will listen to it as we're doing chores around the house and I would catch myself paying attention from time to time.