Right before it's showcase at IFA 2015 tomorrow, Samsung Mobile Press site officially unveiled the Samsung Gear S2.
There are 3 available variants, the (original) Gear S2, Gear S2 Classic and Gear S2 3G. All of these have the Tizen OS. Aside from the new circular display for Samsung wearable, it will also have rotatable bezel.
They have identical specs like 1 GHz dual core processor, 512 MB RAM, 4 GB ROM, IP68 water and dust resistant, 1.2 inch circular Super AMOLED display with 360 x 360 display at 302 ppi, communications features, fitness features which include Nike+ running and S Health, WiFi, Bluetooth 4.1, NFC and wireless charging.
Size and battery will be differences in these 3 iterations. Here are the list
Gear S2: 42.3 x 49.8 x 11.4mm (47g) 250 mAh Li-ion
Gear S2 classic : 39.9 x 43.6 x 11.4mm (42g) 250mAh Li-ion
Gear S2 3G: 44.0 x 51.8 x 13.4 mm (51g) 300mAh Li-ion