"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Early Benchmarks: Dual 1GHz
Initial results appears to be identical... however, base configurations of the Dual 1GHz G4 (non-DDR) have 2MB of L3 cache vs 1MB of L3 cache on the DDR G4.
More extensive benchmarks should appears as more systems are distributed.