It has to do with more than just the browser. You'd have to know what plug-ins or extensions are installed and what kind of websites are being visited, such as those with Flash content.
For Flash-related issues:
Find your Flash version and make sure it's the latest version available. Never install or update Flash from a pop-up on a website. Always go to Adobe's site to get Flash or updates.
Use the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.) Some have reported that using the HTML5 trial decreases performance, rather than increasing it.
There are many factors that impact your battery life. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.
This should answer most, if not all, of your battery questions:
I'm not saying Camino with Flash is going to be better than Chrome without. But this guy had done extensive testing, with CoconutBattery to compare the power consumption, and had come to the conclusion that Camino was the browser that made his battery last the longest.
He wrote a thread about it here on MR, he apparently gets over ten hours out of his battery with his tweaks and software choice.
I wouldn't know if the difference is five or 45 minutes, I'm just answering the guy's question based on the information I have