There are no specific technical specs on the battery size (which is irrelevant since the technology is making smaller batteries more efficient these days)...the number specs on the official Apple page look identical to last years, which is all I care about personally, since both devices have good battery life.
Talk time: Up to 14 hours on 3G
Internet use: Up to 10 hours on 3G, up to 10 hours on LTE, up to 11 hours on Wi‑Fi
HD video playback: Up to 11 hours
Audio playback: Up to 50 hours
Standby time: Up to 10 days