They include messaging with your Oculus pals, along with photo and video sharing and livestreaming to Facebook. You can create events to set up a time to play games with your buddies or arrange meetups, and form parties that all your Oculus friends can join (parties were invite-only until now). Your Facebook friends will also be able to group up with you in VR when you send them links via Messenger.
You won't have to log in with Facebook to use the VR platform. If you do, you'll still keep your existing Oculus friends, username and profile. You can decide to display your real name (as per your Facebook profile) on Oculus and whether to automatically add your Facebook friends as Oculus contacts. You'll have control over what you share from Oculus to Facebook as well, along with who can see those posts.
The ties between Oculus and Facebook services will deepen over time, with new features such as Facebook Group sharing options and watch parties on Quest on the way. A beta for the Facebook Horizon social VR world is also slated for next year.