Facebook has joined the live-stream-video scene — but so far, it’s only for famous people.

The service allows users to broadcast an event and viewers to comment as they’re watching, similar to other live video apps like Periscope. But there are some key differences. The video is streamed through Facebook Mentions, which is available only to public figures with verified Facebook pages as a way to manage interactions with fans. And users can catch the video later if they miss the live version, unlike Snapchat and Periscope, which both delete public videos after 24 hours.

Facebook is joining a competitive market. Periscope is owned by Twitter and reported one million users in the first 10 days after its opening. Snapchat’s curated streams, known as Live Stories, receive an average of 10 to 20 million viewers, Shannon Kelly, a spokeswoman for Snapchat, wrote in an email.

So in the world of live streaming, how does one choose?

Use Facebook if: You want to watch Lindsey Vonn ski down a mountain. Or listen to a new track from Luke Bryan. Or see the NBC newsroom from the perspective of Lester Holt.

Perks: Watching celebrities pretend to be real is fun.

Downside: It’s not available to the masses.

Use Periscope if: You want to get a virtual guitar lesson from John Mayer as much as you want to watch a stranger tour his or her city.

Perks: Anyone can broadcast, and it’s easy to share the stream on Twitter.

Downside: Videos are deleted after 24 hours unless you save them on your phone.

Use Snapchat if: You want to see a collection of edited clips from a range of users at popular events, such as the Lollapalooza music festival and the Quidditch World Cup, or unique locations, like the world’s largest mosque.

Perks: Multiple clips means multiple perspectives, and anyone at the event or location can contribute (although that doesn’t guarantee it will appear in the feed).

Downside: The stream isn’t necessarily in real time, Ms. Kelly, the spokeswoman, said. There is a lag of about an hour between the time users submit a video and the time editors add that clip to the story.