[mardiros]

Twisted is a tcp/udp[/ssl] framework, Tornado is an http one.

In other word, with Twisted, you can write http, ftp, smtp, ... and your are free to write your own protocol.

[dguaraglia]

Well, twisted is an async framework, and that's the important thing. Back in the day I actually wrote a Twisted protocol to send/receive SMS messages from a modem over serial. In total the code was like 100 LOC. That's how flexible, well-organized it is.