Correct, and you will want to have the wifi connection when you are near a hotspot/AP that you can use. It takes less battery to use wifi than the LTE service, although it's probably a tad slower. I wouldn't recommend leaving wifi on all the time though, I'd only turn it on when you know there is a wifi network available that you can use. Otherwise it will be constantly scanning for networks and presenting you with options to connect to them, chewing up the battery even more.