Prius: Can someone explain the power usage meter & specific difference between power mode and Eco mode?

My brother just got me a Prius to replace my old beater Honda and I'm having difficulty understanding the power usage meter (meter on dash with "Charge-Eco-Power") and the difference in the Eco & Power modes. I do understand the charge bit on the meter.

Basically its really all the same mode… Once you get used to it. Eco mode, makes your engine weak… But fuel efficient. I would say it would be like transforming into a 4 cylinder engine… Normal would be 6 cylinder and power would be 8… Obviously not as powerful as a 8 cylinder car… Just a reference… I used to switch modes, now i just stay in normal mode, and use the gas more efficiently than it can… Also the car charges on power mode faster than breaking… Don't leave the ac on when the battery is really low, but heat is fine.

The meter is a relative efficiency meter; it is not really very useful. The Eco and Power modes are really just throttle response modes. It is not very intuitive but there's no more power in the power mode, yet the car will accelerate from one speed to another as much as a second quicker in that mode. The main difference is in whether the hybrid system is smoothing out the driver's throttle commands or responding immediately and decisively. My own preference is to drive in Eco mode because it matches my driving style - looking ahead and avoiding sudden moves. When I'm going to be merging in heavy traffic I prefer Power mode.