The difference is that the rules are rendered using actual CSS syntax, rather than the section heading control. This makes it very easy to scan because as a we

The difference is that the rules are rendered using actual CSS syntax, rather than the section heading control. This makes it very easy to scan because as a web developer, your brain is already trained to parse CSS syntax easily. The controls in the webkit UI may seem richer, but they aren't actually as efficient as the simple code view that Firebug uses.