Either of those radios can use a rechargeable battery, but it's an add on item. You might consider pricing radios that come with a rechargeable battery, because once you do the upgrade you might find yourself spending the same money for a less capable radio.

As for comparing features and deciding what to buy, I'm linking a chart for you below. I can't tell that there is any difference in the build quality as the DX6e is just a DX6 with some features removed.