The Roubaix is built a bit less 'racy'. This mainly means that the handlebars are a bit closer to your upper body and the seat is a bit less sporty, making you sit a bit more upright. This bike also has suspension in the handlebars (Future Shock) and the seatpost can flex within the frame.

The Roubaix is really built for comfort, making it an ideal bike for the more recreational mile-eater. Now don't think it's a less fast bike, as Patrick Lefevere's Quick Step team won several races with it. And who doesn't remember Peter Sagan's victory in Paris Roubaix on his gold S-Works Roubaix?