2 points
I dont know much about it, but Wikipedia says that MTProto is specifically for “secret chats”:
For encrypted chats (branded as Secret Chats), Telegram uses a custom-built symmetric encryption scheme called MTProto.
https://en.m.wikipedia.org/wiki/Telegram_(software)#Architecture
Maybe Wikipedia is misleading here
2 points
*
You’re right, it is misleading. There are different “flavours” of MTProto. See here:
https://core.telegram.org/mtproto
This page deals with the basic layer of MTProto encryption used for Cloud chats (server-client encryption). See also:
Secret chats, end-to-end-encryption
End-to-end encrypted Voice Calls
(The major difference is simply whether the server and client share a key or two clients)
