"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Jaguar 6C115: Final Candidate, Not Gold Master
RailHeadDesign has a screenshot of the wording in the 6C115 release:
Jaguar build 6C115, the GM candidate of Mac OS X version 10.2
According to them 6C116 has already been seeded. While this is all hair-splitting at this point, the take home message is that it appears on-time and near completion.