There is probably no really big difference in battery usage between the two versions. If you notice a difference that's dramatic, it's possibly an issue of settings rather than version. For instance, if you used an update procedure that included wiping the phone, your settings may be different than before.
The one biggest setting issue that I ever found is Wi-Fi sleep policy. Unless I'm traveling or commuting, I'm normally in a strong WiFi signal environment, so preventing the phone from switching to 3G every time it locks increased my battery life 50 to 100 percent. I only have to charge the phone every few days now unless I use it heavily. It's probably especially helpful when there's a lot of synchronization going on.
You can check this under Menu/Settings, Wireless and networks, Wi-Fi settings, Menu/Advanced, Wi-Fi sleep policy. Set to "Never".