Telegram has way, way more features than Signal. First-class clients on every OS, much better behavior for large groups, far more sophisticated and granular permissions system for admins in groups, voice and video messages, folders for chats, etc.
It also has way more security features too, such as the ability for any session to de-auth any other session, while on Signal, only one mobile device is your "primary", so you're screwed if you lose that. Also tons of detailed permissions for who is allowed to see what information of yours and add you to groups. The only thing Signal actually does better is E2EE for groups. I think it's simplistic and short-sighted that many tech people seem to think that "security" means E2EE and absolutely nothing else.
It also has way more security features too, such as the ability for any session to de-auth any other session, while on Signal, only one mobile device is your "primary", so you're screwed if you lose that. Also tons of detailed permissions for who is allowed to see what information of yours and add you to groups. The only thing Signal actually does better is E2EE for groups. I think it's simplistic and short-sighted that many tech people seem to think that "security" means E2EE and absolutely nothing else.