The higher-end Xtreme ($199.99) is the better performing model, featuring a bass-extending radiator to go along with its two drivers, and a high-capacity 6,600 mAh lithium battery that can also be used to charge your smartphone or tablet.
Both speakers feature an integrated USB charging port, IPX4 splash-proof design, Bluetooth 4.0, NFC tap-to-pair technology, and speakerphone capabilities. And like their Rukus predecessors, they have integrated solar panels that trickle charge the speaker in direct sunlight (it's a slow process).
The more affordable Rukus 2 ($99.99) has a much smaller 1,600 mAh rechargeable lithium battery and leaves off the bass radiator, which means it'll be a slightly thinner-sounding speaker. Eton says you can charge the Rukus 2 in 5 hours via the solar panel or 2.5 hours with an AC adapter.
Both models ship in the spring (Q2). I'll be updating this post with further impressions and pictures as we get some hands-on time with the new products at the show.