"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
A9X in 9.7-Inch iPad Pro is Underclocked Compared to 12.9-inch iPad Pro
On its iPad comparison page, Apple lists the specs of the A9X in both of the iPad Pros, comparing them to the A7 chip in the iPad Air, iPad mini 2/3, and iPhone 5s. The 12.9-inch iPad Pro lists a 2.5x faster CPU and 5x faster graphics, while the 9.7-inch iPad Pro lists a 2.4x faster CPU and 4.3x faster graphics.
Apple has a history of underclocking the chips used in smaller devices. The iPad mini 2 and the iPad Air both used the same A7 chip, but while the iPad Air clocked in at 1.4GHz, the iPad mini 2 ran at 1.3GHz.
It's likely Apple is underclocking the A9X chip in the 9.7-inch iPad Pro due to its smaller body, which may be unable to dissipate heat as well as the larger 12.9-inch iPad Pro, The performance difference between the two tablets is likely to be unnoticeable in real world conditions, and even underclocked, the 9.7-inch iPad Pro is offering some significant performance improvements over the 9.7-inch iPad Air 2.
Aside from the slightly lower clock speed, the 9.7-inch iPad Pro has several features that set it above the 12.9-inch iPad Pro, including a 12-megapixel camera with a rear flash and a new True Tone display feature that adjusts the screen's temperature based on ambient lighting.
The 9.7-inch iPad Pro will be available for order starting this Thursday, with in-store availability and shipments starting the following Thursday, on March 31. Pricing for the new iPad Pro starts at $599.
Update: Geekbench benchmark testing conducted by TechCrunch's Matthew Panzarino suggests the A9X processor in the 9.7-inch iPad Pro runs at 2.16GHz, compared to 2.24GHz in the 12.9-inch iPad Pro.
Here's a single Geekbench run with stats on iPad Pro 9.7" pic.twitter.com/vwqlKtsIUm— Matthew Panzarino (@panzer) March 22, 2016