"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Teardowns Detail Minor Differences Among Wi-Fi, GSM, and CDMA iPad 2 Models
The most obvious physical difference between the 3G models is the micro-SIM card slot along the upper left edge of the GSM model, required for providing the device with subscriber information. The micro-SIM card slot itself is actually attached to the headphone jack cable on the GSM model, while the CDMA model lacks the slot entirely as subscriber information is instead hosted directly on the WWAN board inside the device.
iPad 2 antenna configurations: GSM (top), CDMA (middle), and Wi-Fi (bottom)
Given the differences in frequencies used for the GSM and CDMA network standards, it is also unsurprising that the two 3G iPads offer slightly different antenna configurations, with the CDMA version offering one more antenna than the GSM version, similar to the iPhone 4.
iPad 2 logic boards: Wi-Fi (top), GSM (middle), and CDMA (bottom)
And finally, the three iPad 2 variations also exhibit differences in their logic boards, with the 3G models containing WWAN board extensions housing the hardware supporting cellular connectivity. Unsurprisingly, the CDMA model contains essentially the exact same chips, including the Qualcomm MDM6600 baseband chip, as the CDMA iPhone 4. The GSM model, on the other hand, primarily relies on Infineon chips for its connectivity.