Different trim levels explained:
The Z06 will offer three, increasing levels of aerodynamic downforce:
The standard Z06 features a front splitter, spats around the front wheel openings, a unique carbon-fiber hood with a larger vent, and the rear spoiler from the Corvette Stingray’s Z51 Performance Package.
An available carbon-fiber aero package - in either black or a visible carbon-fiber finish - adds a carbon fiber front splitter with aviation-style winglets, carbon fiber rocker panels, and a larger rear spoiler with a fixed wickerbill – a small, vertical tab at the edge of the spoiler that significantly increases downforce.
The available Z07 package add larger winglets to the front splitter, along with an adjustable, see-through center section on the rear spoiler for track use. With this package, the Corvette Z06 delivers the most aerodynamic downforce of any production car that GM has tested.
On page 4 of this pdf you can see a comparison chart: http://www.corvettemuseum.org/specs/2015/2015Corvette_What'sNew_Final.pdf