As for appearances, the Graphite Edition adds black trim almost everywhere, including the roof rails, grille, fog light surrounds, and window surrounds. It also adds 22-inch wheels, regardless of whether it's just the appearance version or the performance version. The appearance package has machined-finish wheels, and the performance package has black painted wheels.
As previously mentioned, the performance version of the Graphite Edition adds magnetic suspension and the 6.2-liter V8 with 420 horsepower and 460 pound-feet of torque found on the Denali and the Tahoe and Suburban RSTs. It's coupled to a 10-speed automatic transmission, and gets a rear axle ratio of 3.23:1. It also gets a few other Denali features such as a color heads-up display, Bose noise cancellation, a 170-amp alternator, and a trailer brake controller. The Graphite Edition can be had with both two-wheel drive or four-wheel drive.
The Graphite Edition can only be had on Yukon and Yukon XL SLT models. Pricing hasn't been announced yet, but it's likely it will be a bit more affordable than buying a Denali model.