What's the difference between the battery of iPhone 5s vs iPhone 5?
There are slight improvements to the battery capacities of the 5S and 5C over the 5.


iPhone 5 - 1440mAh &lt;- 5.45Whr at 3.8V
iPhone 5c - 1508mAh &lt;- 5.73Whr at 3.8V
iPhone 5s - 1558mAh &lt;- 5.92Whr at 3.8V


Source



In terms of battery life comparison for 5 vs. 5c vs. 5s, they ran some benchmarks in their review.  In some tasks the 5c/5s are better than the 5, in others the 5 is better.  With the exception of their Wifi browsing test, the new phones are comparable to the 5, with there being less than an hour difference in battery life.  In the Wifi browsing test though, the new phones ran out of juice .57 hours sooner (5c) and 1.3 hours sooner (5s).