"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Apple Launches USB-C Charge Cable Replacement Program for Retina MacBook
According to Apple, affected cables may cause the MacBook to not charge or to charge intermittently when it is connected to a power adapter. Cables with the issue can be identified by their labeling, which reads "Designed by Apple in California. Assembled in China." Redesigned cables have the same text, but also include a serial number.
Apple is providing new, redesigned USB-C charge cables to MacBook owners with faulty cables at no cost. In addition to cables that shipped with the MacBook, the replacement program also includes faulty cables that were sold as standalone accessories.
Customers who supplied a valid mailing address when registering their product or purchasing it through the Apple Online Store will receive their new cables automatically, while other eligible MacBook owners can contact Apple Support, find an Apple Authorized Service Provider, or visit an Apple retail store to get their cables replaced. Affected USB-C charge cables can be replaced under this program until June 8, 2018.
The Retina MacBook first went on sale in April of 2015, so the problematic cables were sold for approximately two months before a redesigned version was released.