The radios are confusing to just about everyone, not only you.
The RHB nav Radio (430N) has garmin based software. The other radio that could be in Overlands built since January is a RHR (730N) which is a replacement for the earlier RER (also 730N). The RHR would have the same look and feel as the RER. The same radios are used across the Chrysler line.
Many here prefer the RHB for the superior Garmin nav software, others prefer the RHR for its voice commands and dead reckoning features. They both have their quirks and distractors. The RHR is like a $300 extra cost option over the RHB base radio.
Make sure the dealer updates the RHB, with the recently released upgrade, before you pick it up. You will like the radio better, especially if you use it with an iPod or smart phone. (TSB 08-036-11 I think)
A description here;