The two sites serve as sort of ‘companion’ services to Twitter, in so far that you have to use your twitter log in to sign up and in to the sites.
The Branch website will be a platform for Twitter users that like to talk a lot, those that are more vocal. It means that you won’t have to butt in to other people’s conversations and there is no 140 character limit which means you can have longer more in-depth conversations.
Medium will allow members to post articles, pictures and media, but it allows you to collaborate in that you can choose whether you want people to be able to add their media to yours or if it’s just you that can post. Think of it as a publishing format, but crossed with Pinterest. It’s a very interesting idea, and of course, you will need to sign in with your Twitter.
Currently both sites are in beta, invitational only phase, you can of course request an invite, but take your time, relax, the sites look as though they are built to be smooth and serene, so try to take them that way.