There's a TOR browser, but calling tor "just a browser" is really odd and not really correct. The TOR project is the routing protocol that bounces your traffic around. You can do so through the TOR browser, but the browser isn't TOR. It also isn't the only way to use TOR.
Also, while HTTPS is close to universal now, it's still possible to use HTTP and theoretically a malicious exit node could modify any unencrypted traffic.