Telegram has E2E encryption, but only in Secret Chats: https://telegram.org/faq#secret-chats
You want secret chat for groups? Sorry, can't do. (Signal can.)
You want secret chats for desktop messages? Sorry, can't do. (Signal can.)
You want everything end-to-end encrypted by default? Sorry, can't do. (Signal. Can.)
Telegram has E2E encryption, but only in Secret Chats: https://telegram.org/faq#secret-chats