Both are built around things that do not stay forever. The difference is what happens to the rest — the account, the location, and what the company can read.
Photos and messages that disappear: view-once, or self-destructing a set number of seconds after being opened.
AR masks on video calls, including ones you generate from a written description.
A map-ish view of what is around you.
What Tex does differently
Signing up takes an @username and a password. No phone number, no email, no real name.
Text chats are end-to-end encrypted — the key is generated on your device and never leaves it, so what reaches the server is ciphertext.
You can lock a single message behind a password, so it only opens for whoever knows it.
What you leave in a place stays in that place: whoever walks by can find it later, which is not what a story is.
Where Snapchat is better
This section is here because a comparison where the author wins everything
is not worth reading. These are real, and they are the reasons to stay where you are.
Everyone is already on Snapchat. That is the whole point of a social app, and Tex does not have it.
Snapchat's camera and its filters are years ahead of anything Tex renders in a browser.