Volts,,, 18 or 24???

I've seen the "drill auger" in action and I'm VERY impressed. The one I saw was a 18V Ryobi. My question is this,,, what benefit is there to having a 24V rather than 18V?? Will you get more "torque" with a 24V or is it just more battery life?? I have a "cheap" 18V that I think just doesn't have the "strength". Has anyone used a 24V ?? Are there any pluses or minuses to the 24V?? Thanks in advance.