Why life is different for the same battery

[#1]

I have Xperia mini, Android 2.3.4.

And I have a question

Why life expectancy for the same battery differs

SE sells other similar phones: Xperia min pro, Live with Walkman, with same battery capacity, screen size....

But the operating time of phones in a conversation mode (GSM) essentially differs!

Mini = 4 hours 30 min, MiniPro = 5 hours 25 min, Live with Walkman = 14 hours 15 min.

[ashvar · Accepted solution]

All these phones have different hardware specs, and display pixels also vary some times, hence different battery consumption