Supergroups are a powerful tool for building communities and can support up to 200,000 members each.
Technically, supergroups are actually channels: they are represented by channel constructors, with the megagroup flag set to true.
Gigagroups are something inbetween a channel and a supergroup.
-An admin, when prompted by the API using suggestions », can convert a megagroup into a gigagroup using channels.convertToGigagroup (one way only). After that, only admins will be able to write in the group (like when send_messages rights are disabled for all group participants by default), but the participant limit is removed and the group can become much bigger than a supergroup (e.g. >200,000 currently).
+An admin, when prompted by the API using suggestions », can convert a megagroup into a gigagroup using channels.convertToGigagroup (one way only).
+After that, only admins will be able to write in the group (like when send_messages rights are disabled for all group participants by default), but the participant limit is removed and the group can become much bigger than a supergroup (e.g. >200,000 currently).
Also, one can't invite people into gigagroups and participants of voice chats in gigagroups are muted by default.
Channels and supergroup can be created using the channels.createChannel method, by setting the appropriate broadcast or megagroup flags.
Supergroups can also be assigned a geo_point to become geochats.