With the exception of the SIM card slot, located on the lower left-hand-side of the device, and the associated internal cellular radios, the LTE variant is identical to the 64GB version of the Surface 2. The Surface 2 LTE is shipped SIM-unlocked and supports LTE bands 4,7, and 17.
From the Surface Blog:
In launching this new version of Surface 2, we’re adding the power and reach of AT&T’s 4G LTE network to an already fantastic device. Along with cellular connectivity, all of the refinements that went into Surface 2 are here: the increased speed and battery life, the dual-position kickstand, Microsoft Office Home & Student 2013 RT and Outlook 2013 RT, the full HD screen, the upgraded front- and rear-facing cameras and full-size USB 3.0 port, just to name a few.
An obvious pricing comparison can be made with the LTE equipped Lumia 2520. While the Lumia 2520 does have less internal memory (32GB rather than 64GB) and misses out on some of the Surface 2 extras (e.g. 200GB OneDrive space), it is considerably cheaper at $499 (SIM-free, or $399 with AT&T). While the $180 / $280 price difference is partly the result of small specification differences, the cost of materials, construction technique, and margin level may also be contributory factor.