There are several differences between group chats and multi-person chats.
Group chats
With group chats, you can set up a group name and profile photo. You can also use convenient features like Albums and Notes.
However, the friends you invite need to tap the Join button to participate in the group.
To start a group chat:
1. Tap the Friends tab on the main menu.
2. Select the group name and tap Group chat.
Note: If you want to create a group, please see here.
Multi-person chats
Several friends can start chatting as soon as they're invited to a multi-person chat.
Compared to groups, the features you can use are limited, but multi-person chats offer the advantage of letting you easily create chat rooms with several friends.
To start a multi-person chat:
1. Tap the Chats tab on the main menu.
2. Tap the speech bubble icon at the top of the screen.
3. Select who you want to add and tap Chat.