Private groups are not accessible to contacts other than the ones present in the group. Only group admin can add/remove members in the group. You can create private groups to facilitate close, WhatsApp style interactions. For example, doctor-patient chats.
Users will be able to search and join Public groups. Any group member can add/remove members in this group. For example, Public group can be used to create area-wise communities in a social app where users can search their area's community and join.
A message can be sent to several contacts at once. Message sent in the broadcast group is received by the members of the group as one to one chat thread. Only the sender can see the broadcast group. The broadcast group works on a similar behavior as that of WhatsApp broadcasts.
Used for free-flowing chats such as live streaming chats, live event chats etc. You need not add any member to this group. All users present on the chat screen will receive messages via MQTT (publish/subscribe pattern). Push notifications are not supported in Open groups.
Used for the purpose where dealers are selling products and any particular user wants to chat about multiple products with the same dealer. At that time, it is required to show two different chat threads in the conversation history as the context (product) of the chats is different.
Used for creating Friends/Favorites contact List. These lists can be maintained on the application level and any member of the group can access it. For example, an event management company can use the lists to maintain attendees of an event at one place.
Best suited for people who want to use Applozic's another product, Kommunicate. These groups are specifically built for the purpose of customer support chat and may contain multiple team members and chatbots talking to a user.
Note: If you have doubts in choosing which group type works the best for you, please choose Public groups as it served most of the use-cases.