Nothing. It accelerates a tiny bit quicker so some say it is more fun to drive and some people like the look a little better. Really it's personal choice, they are both great cars. If you're looking at new cars, the new Corolla is really nice. It is nicer looking than older ones and gets better gas mileage than older corollas or new civics. It is also much roomier than the civic, especially in the back seat. This is the biggest reason I prefer it. Both are very reliable but the Corolla actually scores just slightly better in most long-term reliability rankings that I have seen.