Today, peer-to-peer IMs use AES 256 encryption while IMs passed through cloud use TLS.
AES 256 is an encryption algorithm while TLS is an encryption protocol (which includes a mechanism for selecting an algorithm, which is fairly unlikely, today, to be anything other than AES 256 but could be something weaker or stronger).
You're comparing chalk with ... not cheese, but with some method for selecting a piece of chalk.
Biting the hand that feeds IT
