The new feature allows readers and Page owners to start conversation threads, so that discussions about a photo, question or topic can be grouped into a more easily-identified area. It can also allow celebrities or even journalists to hold Q&As with their audience, by being able to answer users' questions directly. Comments can also be put higher if they are more relevant, gain replies or are more positive (if a user wants).
An example of the changes, tested earlier this year:
For more about recent Facebook changes, click here.